diff --git a/browser/components/about/AboutRedirector.cpp b/browser/components/about/AboutRedirector.cpp
index ef458538d51f..ccbdd59090fa 100644
--- a/browser/components/about/AboutRedirector.cpp
+++ b/browser/components/about/AboutRedirector.cpp
@@ -84,7 +84,7 @@ static const RedirEntry kRedirMap[] = {
     nsIAboutModule::ALLOW_SCRIPT |
     nsIAboutModule::HIDE_FROM_ABOUTABOUT },
   // Actual activity stream URL for home and newtab are set in channel creation
-  { "home", "about:blank", ACTIVITY_STREAM_FLAGS },
+  { "home", "about:blank", ACTIVITY_STREAM_FLAGS | nsIAboutModule::MAKE_LINKABLE }, // Bug 1438367 to try removing MAKE_LINKABLE again
   { "newtab", "about:blank", ACTIVITY_STREAM_FLAGS },
   { "library", "chrome://browser/content/aboutLibrary.xhtml",
     nsIAboutModule::URI_MUST_LOAD_IN_CHILD |
diff --git a/browser/extensions/activity-stream/install.rdf.in b/browser/extensions/activity-stream/install.rdf.in
index f0a9a48a8e69..e94d5a01cb8c 100644
--- a/browser/extensions/activity-stream/install.rdf.in
+++ b/browser/extensions/activity-stream/install.rdf.in
@@ -8,7 +8,7 @@
     <em:type>2</em:type>
     <em:bootstrap>true</em:bootstrap>
     <em:unpack>false</em:unpack>
-    <em:version>2018.05.04.1204-6a362de7</em:version>
+    <em:version>2018.05.11.1144-66b23ff4</em:version>
     <em:name>Activity Stream</em:name>
     <em:description>A rich visual history feed and a reimagined home page make it easier than ever to find exactly what you're looking for in Firefox.</em:description>
     <em:multiprocessCompatible>true</em:multiprocessCompatible>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream-prerendered.html
index b7f6149db813..dd7406416feb 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream.html
index 338f6a5d9ffe..36b32f19141d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ach/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/an/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/an/activity-stream-prerendered.html
index 22e15b327422..6d3db90ea1f1 100644
--- a/browser/extensions/activity-stream/prerendered/locales/an/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/an/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/an/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/an/activity-stream.html
index 65b7ac4445ea..d6948f85cfd9 100644
--- a/browser/extensions/activity-stream/prerendered/locales/an/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/an/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream-prerendered.html
index 2883cb88f285..0e6cc7c4c28d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream.html
index 7cb3a150198a..24b8fa68434b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ar/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream-prerendered.html
index 2719dc16c9cf..e50692b5223f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream.html
index 791d01f34a10..5e1f54dd7e1f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ast/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/az/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/az/activity-stream-prerendered.html
index c3846e0da5c2..0e5768dfb50c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/az/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/az/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/az/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/az/activity-stream.html
index 3b39e59bf504..3fedc85c4d55 100644
--- a/browser/extensions/activity-stream/prerendered/locales/az/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/az/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/be/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/be/activity-stream-prerendered.html
index 73b7a13cb7e2..8f79216bc6a2 100644
--- a/browser/extensions/activity-stream/prerendered/locales/be/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/be/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/be/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/be/activity-stream.html
index 419b217db407..55e2517df581 100644
--- a/browser/extensions/activity-stream/prerendered/locales/be/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/be/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream-prerendered.html
index cecf760d2bbc..6dba40734e6f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream.html
index 6f8ef53a7051..e42910426e90 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bg/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream-prerendered.html
index dec3b73860ad..5133c2dfd5d5 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream.html
index bbd67a163c70..03f0bcc121f4 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bn-BD/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream-prerendered.html
index 3f32ef24b359..1b036d730ea2 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream.html
index 9fe2eb89f879..ee83a0c74d67 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bn-IN/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/br/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/br/activity-stream-prerendered.html
index e69bf0e53a92..5334c989592a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/br/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/br/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/br/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/br/activity-stream.html
index 47f337af9a44..960cd6a4f6af 100644
--- a/browser/extensions/activity-stream/prerendered/locales/br/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/br/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream-prerendered.html
index 564b5f22c2d6..c1d50dd8c1e0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream.html
index e7e919860949..fea2146b7c72 100644
--- a/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/bs/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream-prerendered.html
index 050c337c5433..5dda2c424447 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream.html
index 8d65633516cf..c2151ad76419 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ca/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream-prerendered.html
index 1f6c08ce48ab..ba275dd0471b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream.html
index 1a85741d3f40..f237c3d8e048 100644
--- a/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/cak/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream-prerendered.html
index e3d4eeddd012..ddbf3a7e8780 100644
--- a/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream.html
index bf56f559c459..398da8493c02 100644
--- a/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/crh/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream-prerendered.html
index c89bde1018ab..22170bfa5424 100644
--- a/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream.html
index 95b7d06d9ff7..4285d67d2637 100644
--- a/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/cs/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream-prerendered.html
index 7359ff34fbc5..9b8f6b6af5c0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream.html
index 0c844f3b0d1a..ec631863ba26 100644
--- a/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/cy/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/da/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/da/activity-stream-prerendered.html
index b39a81b001e6..bd778942fe3b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/da/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/da/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/da/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/da/activity-stream.html
index bac2719db6f7..04ae1696e9d8 100644
--- a/browser/extensions/activity-stream/prerendered/locales/da/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/da/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/de/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/de/activity-stream-prerendered.html
index e762a940c126..04c706fe66a9 100644
--- a/browser/extensions/activity-stream/prerendered/locales/de/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/de/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/de/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/de/activity-stream.html
index 3742b0de8189..52840618f87b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/de/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/de/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream-prerendered.html
index 363f29d22bb7..db9b4b12fdc5 100644
--- a/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream.html
index acf56df304ef..8ba9dc98b809 100644
--- a/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/dsb/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/el/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/el/activity-stream-prerendered.html
index 8b30084533e6..0b1632f114de 100644
--- a/browser/extensions/activity-stream/prerendered/locales/el/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/el/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/el/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/el/activity-stream.html
index 6770e263ac91..43038c0c6209 100644
--- a/browser/extensions/activity-stream/prerendered/locales/el/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/el/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream-prerendered.html
index af369392bb44..b8485f7a341c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream.html
index 5b0d446e0cce..cdfab3369533 100644
--- a/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/en-CA/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream-prerendered.html
index 0a9cc2059315..385d9065b04c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream.html
index 7860d9aa2d70..6db5c5f540b3 100644
--- a/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/en-GB/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream-prerendered.html
index 7658f7d15c08..baa61d70e321 100644
--- a/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream.html
index 5960f039900b..7143b06c9d7f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/en-US/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream-prerendered.html
index 27a518bce17b..aa999fa7b075 100644
--- a/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream.html
index 67f721abcd49..23750016c70a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/eo/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream-prerendered.html
index ca5c275424e6..6545404808db 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream.html
index a755bb77f79b..23195f500618 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-AR/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream-prerendered.html
index 3233bda3c973..84d21b62b034 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream.html
index 3ba24aa04cbf..1760c9497721 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-CL/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream-prerendered.html
index 58f19de32b01..2e9db74e827b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream.html
index d6361e1dfc39..fb1164bb1c17 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-ES/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream-prerendered.html
index 66c4ff868d70..68c3608a1882 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream.html
index 050234720db3..49e4c81fd8cf 100644
--- a/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/es-MX/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/et/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/et/activity-stream-prerendered.html
index 9129e599d468..f28b2abd671c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/et/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/et/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/et/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/et/activity-stream.html
index 3f543f9c0b09..57061d2b64f0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/et/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/et/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream-prerendered.html
index e621ddf3ce6b..010aa06feb40 100644
--- a/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream.html
index bc9a54679529..72f8697adbc6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/eu/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream-prerendered.html
index b694fd7caff3..f23ee06e1a1b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream.html
index 56b4de5174b3..07239ea539c0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fa/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream-prerendered.html
index 6e0da43e96a4..1b7579f052b8 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream.html
index 5c94fa2dd9c3..67b5e5135b4d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ff/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream-prerendered.html
index 10886f40d6ba..e5812987a010 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream.html
index 1fa44170ffd3..dc8af2f7c5e2 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fi/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream-prerendered.html
index 012f6f49cfd0..34fbe104cfe6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream.html
index f6de3d50df63..0fc6c633a0e3 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fr/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream-prerendered.html
index 55cf984780a0..99bd434de786 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream.html
index 58840287818b..cb7cae951e91 100644
--- a/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/fy-NL/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream-prerendered.html
index 2ba7e5f0174c..fdd4ff01502b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream.html
index 5a115338c0db..6fafefd356a6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ga-IE/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream-prerendered.html
index 10f66d086a48..ddff46dd8c50 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream.html
index 687075637856..0afa76024ce6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gd/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream-prerendered.html
index 8317178ef5a2..fe0cfb761c6d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream.html
index d08a939f60d7..e583f39ad81d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gl/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream-prerendered.html
index b3aac392a949..46a4cf89af17 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream.html
index 1f3288be4b8d..8b02d6fcdda7 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gn/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream-prerendered.html
index 066e1ffc7b89..3554abe3edfd 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream.html
index 4971ed6f0f0c..4f49b786d044 100644
--- a/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/gu-IN/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/he/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/he/activity-stream-prerendered.html
index 5b12fbb9a529..efe2c92a62b0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/he/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/he/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/he/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/he/activity-stream.html
index 178724160d7d..96822ea87132 100644
--- a/browser/extensions/activity-stream/prerendered/locales/he/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/he/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream-prerendered.html
index 137e1951a2ab..05ec8dc43af7 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream.html
index b44c6294bd86..ec89c0348e93 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hi-IN/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream-prerendered.html
index 83e68120488f..c6c2461fda02 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream.html
index 11424327a686..e43f2915133c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hr/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream-prerendered.html
index 72563bf46316..1095fd8734a0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream.html
index aaa7736c28e3..efd0be15857f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hsb/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream-prerendered.html
index f169123ce4be..19046add7002 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream.html
index 34db09afb2ad..222c644353de 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hu/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream-prerendered.html
index 6c07251700d9..accc61cff266 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream.html
index 37afed335dab..ddf5d6a76680 100644
--- a/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/hy-AM/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream-prerendered.html
index 6c0dee5a577a..19eeee9226cd 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream.html
index cf4b7fc07404..095c5c71d771 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ia/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/id/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/id/activity-stream-prerendered.html
index f92d1fe1c6a4..3bf6b92d5fac 100644
--- a/browser/extensions/activity-stream/prerendered/locales/id/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/id/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/id/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/id/activity-stream.html
index 5aeb757789ee..6e5dfdd9c2e8 100644
--- a/browser/extensions/activity-stream/prerendered/locales/id/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/id/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/it/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/it/activity-stream-prerendered.html
index e72558a1aaeb..9a6676f5cabf 100644
--- a/browser/extensions/activity-stream/prerendered/locales/it/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/it/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/it/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/it/activity-stream.html
index 223fedcfebe7..6497befecd0b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/it/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/it/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream-prerendered.html
index f30274228e1b..94e67cd5ad19 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream.html
index a6a954667b0d..fcead44485b4 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ja/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream-prerendered.html
index 2f13e9d7c23e..e0d02a4611ce 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream.html
index 97d952c1dc29..275abaec6396 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ka/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream-prerendered.html
index 763dd76a6890..6d37ac9049ee 100644
--- a/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream.html
index c0c2695abf8c..ece8960e5245 100644
--- a/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/kab/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream-prerendered.html
index 64bc622509fe..258b03558ca1 100644
--- a/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream.html
index 9c35cdb80d46..25ed1a7ffa33 100644
--- a/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/kk/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/km/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/km/activity-stream-prerendered.html
index cf2c062cb868..9d3f0f25e64f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/km/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/km/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/km/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/km/activity-stream.html
index f07f7b271af2..aad0d908e9b3 100644
--- a/browser/extensions/activity-stream/prerendered/locales/km/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/km/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream-prerendered.html
index 21308b7ff4a4..a1b484003d3a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream.html
index 3a5bbc0f84e9..0eedf2787f56 100644
--- a/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/kn/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream-prerendered.html
index 8f39aefb0b12..a01c63cc8787 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream.html
index 6cede1680f01..bc46e7d3562f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ko/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream-prerendered.html
index 14737952b673..260b50a593ca 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream.html
index ae7303ca25f6..801f28e71873 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lij/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream-prerendered.html
index 165663320a9a..56c5da7dc93c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream.html
index 7b572f2df71c..91621b97c725 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lo/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream-prerendered.html
index 32f740f96e42..3be5e9345a6e 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream.html
index 11069827bb1d..796caaeff42d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lt/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream-prerendered.html
index b51ef1bbf90b..3fa04a453ef9 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream.html
index 0fed22f5b900..d78f598e523b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ltg/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream-prerendered.html
index 4a4e5c180e92..c6df3b8407d6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream.html
index b2cbca54a3fd..99c575a6af13 100644
--- a/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/lv/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream-prerendered.html
index 860bb18dee5a..59f16cff7c17 100644
--- a/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream.html
index cd13d7f5c633..0bfe27d64d24 100644
--- a/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/mk/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream-prerendered.html
index 724c78942889..1c7c06492f95 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream.html
index 4d6fe9cc8849..9e3d4c0c72c1 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ml/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream-prerendered.html
index 83f75e054462..b4b0c165c993 100644
--- a/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream.html
index c8cba2f3c45b..a7aca5044193 100644
--- a/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/mr/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream-prerendered.html
index a05294e438d7..e0f24a0eff49 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream.html
index 4cc7efbdc673..0d91aa265738 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ms/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/my/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/my/activity-stream-prerendered.html
index b0dc96f305fb..a40270f77771 100644
--- a/browser/extensions/activity-stream/prerendered/locales/my/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/my/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/my/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/my/activity-stream.html
index ff4a67225e35..6c3c0ba7399a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/my/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/my/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream-prerendered.html
index d2f05f3b693f..72b5c5ac3c5d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream.html
index b3f54fc01314..23c74af4089d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/nb-NO/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream-prerendered.html
index 7b080c5d70ca..0311ac16ea61 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream.html
index 51fb5049dfbc..453fa77531e4 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ne-NP/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream-prerendered.html
index 9272236dfde6..544874c6dd0d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream.html
index 736d919c4699..1c331596fa5d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/nl/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream-prerendered.html
index 3d6c2e6d03da..db8ad86e705a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream.html
index 4e559cffcbc0..3a4e2cf06f68 100644
--- a/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/nn-NO/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream-prerendered.html
index 1e9a30907a28..e4e5358a4902 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream.html
index 316b7a9ed6af..b96337f5b4d7 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pa-IN/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream-prerendered.html
index 5b3dfb1ad664..10cab7528350 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream.html
index 340360ce2ffb..8b12a4105c82 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pl/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream-prerendered.html
index cee9b48d0ad8..0e788e570cd7 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream.html
index b54f71643bd3..272878cc50d6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pt-BR/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream-prerendered.html
index 963aa06bb42a..5a6c0101ffb5 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream.html
index 663c7e13f0a0..60e827b648c2 100644
--- a/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/pt-PT/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream-prerendered.html
index 1fa9bb193f0c..76fba13eeaf0 100644
--- a/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream.html
index edb8dac78d41..e72a39d8f061 100644
--- a/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/rm/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream-prerendered.html
index 8c810243622d..aab6bbaf6360 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream.html
index db3ad5a7e99b..ccae0db4467b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ro/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream-prerendered.html
index d02792f3829d..0a1375e23d6e 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream.html
index abc32869f766..29e8c8e2a607 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ru/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/si/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/si/activity-stream-prerendered.html
index 12a686298fef..2383fa909d6a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/si/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/si/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/si/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/si/activity-stream.html
index 2a0302f3f66e..67e147f23a9a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/si/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/si/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream-prerendered.html
index 0b01b0d506a7..49181ce16cd1 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream.html
index 4b05ab62b4d3..1579cd120aab 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sk/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream-prerendered.html
index 4e3a55a1ce3a..6d001f2af1b3 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream.html
index ff62d833853d..d3403c4a116d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sl/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream-prerendered.html
index 4679931cbebb..09095f0565b2 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream.html
index 9eca2990bfd7..e50be44b62cd 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sq/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream-prerendered.html
index e98c65b80629..669461088e56 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream.html
index f5c83e5a42c9..6d4134363ead 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sr/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream-prerendered.html
index a2c2aefa87f6..f00ba773955f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream.html
index f440f29c6928..fefc7d681eac 100644
--- a/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/sv-SE/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream-prerendered.html
index eb08f1ff2558..c65486809dc3 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream.html
index a556fa718ca9..1c8eb1a6a9a5 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ta/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/te/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/te/activity-stream-prerendered.html
index a0ba33da86ab..0a82fc431526 100644
--- a/browser/extensions/activity-stream/prerendered/locales/te/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/te/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/te/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/te/activity-stream.html
index 5bf9ab440d62..04c5402c89ed 100644
--- a/browser/extensions/activity-stream/prerendered/locales/te/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/te/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/th/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/th/activity-stream-prerendered.html
index 93223111e150..e86283f87e52 100644
--- a/browser/extensions/activity-stream/prerendered/locales/th/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/th/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/th/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/th/activity-stream.html
index 9c22907a910c..511ca1b8ca0a 100644
--- a/browser/extensions/activity-stream/prerendered/locales/th/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/th/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream-prerendered.html
index d5a1cfcaa8c0..4f866ccc09cb 100644
--- a/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream.html
index 95fbfd7b3ea3..8bf20058788d 100644
--- a/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/tl/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream-prerendered.html
index 1bc6fae8e220..2209e8165e90 100644
--- a/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream.html
index 215739cba725..1a29f7a6485e 100644
--- a/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/tr/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream-prerendered.html
index 0ab18780e6f1..1f1984515067 100644
--- a/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream.html
index 68ba212ff8c2..7a13eacf12b6 100644
--- a/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/uk/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream-prerendered.html
index 128e9a7e8fe1..8e3a6b7363bb 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream.html
index c93d6cc6bb3d..2a3ec178f707 100644
--- a/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/ur/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream-prerendered.html
index 2fb47058153e..582e3ce05ced 100644
--- a/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream.html
index 068d17bff242..fb39aaa92784 100644
--- a/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/uz/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream-prerendered.html
index e8ca3c43d9d9..9783efe6a8b7 100644
--- a/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream.html
index 1d9e512d9f1a..2694781660ad 100644
--- a/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/vi/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream-prerendered.html
index 3999929344da..bc847be4698c 100644
--- a/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream.html
index 18808b5cdc80..b284aaa1d50f 100644
--- a/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/zh-CN/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream-prerendered.html b/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream-prerendered.html
index b35b9be7ce75..68b93512149b 100644
--- a/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream-prerendered.html
+++ b/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream-prerendered.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream.html b/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream.html
index 8a9ae0246efb..74e0d5fbdf68 100644
--- a/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream.html
+++ b/browser/extensions/activity-stream/prerendered/locales/zh-TW/activity-stream.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/static/activity-stream-debug.html b/browser/extensions/activity-stream/prerendered/static/activity-stream-debug.html
index cf6f314fdeed..41cecde5b5c1 100644
--- a/browser/extensions/activity-stream/prerendered/static/activity-stream-debug.html
+++ b/browser/extensions/activity-stream/prerendered/static/activity-stream-debug.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -33,6 +39,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>
diff --git a/browser/extensions/activity-stream/prerendered/static/activity-stream-prerendered-debug.html b/browser/extensions/activity-stream/prerendered/static/activity-stream-prerendered-debug.html
index 97418c3817dd..ea30c13c54a9 100644
--- a/browser/extensions/activity-stream/prerendered/static/activity-stream-prerendered-debug.html
+++ b/browser/extensions/activity-stream/prerendered/static/activity-stream-prerendered-debug.html
@@ -13,7 +13,13 @@
     <div id="snippets-container">
       <div id="snippets"></div>
     </div>
-    <script>
+    <script>(() => {
+// Clear out any prerendered content if we shouldn't continue loading
+if (top !== window) {
+  document.documentElement.innerHTML = "";
+  return;
+}
+
 // Don't directly load the following scripts as part of html to let the page
 // finish loading to render the content sooner.
 for (const src of [
@@ -34,6 +40,6 @@ for (const src of [
   script.async = false;
   script.src = src;
 }
-    </script>
+    })();</script>
   </body>
 </html>