diff --git a/accessible/tests/mochitest/elm/test_shadowroot.html b/accessible/tests/mochitest/elm/test_shadowroot.html
index d5f05d263c37..4f5d5eb03356 100644
--- a/accessible/tests/mochitest/elm/test_shadowroot.html
+++ b/accessible/tests/mochitest/elm/test_shadowroot.html
@@ -25,7 +25,7 @@
     SimpleTest.waitForExplicitFinish();
     SpecialPowers.pushPrefEnv({
       set: [
-        ["dom.webcomponents.enabled", true]
+        ["dom.webcomponents.shadowdom.enabled", true]
       ]
     }, function() {
       // This test loads in an iframe, to ensure that the element instance is
diff --git a/accessible/tests/mochitest/hittest/test_shadowroot.html b/accessible/tests/mochitest/hittest/test_shadowroot.html
index 4cb4e9bea64a..d8a959ba469e 100644
--- a/accessible/tests/mochitest/hittest/test_shadowroot.html
+++ b/accessible/tests/mochitest/hittest/test_shadowroot.html
@@ -25,7 +25,7 @@
     SimpleTest.waitForExplicitFinish();
     SpecialPowers.pushPrefEnv({
       set: [
-        ["dom.webcomponents.enabled", true]
+        ["dom.webcomponents.shadowdom.enabled", true]
       ]
     }, function() {
       // This test loads in an iframe, to ensure that the element instance is
diff --git a/accessible/tests/mochitest/treeupdate/test_bug1276857.html b/accessible/tests/mochitest/treeupdate/test_bug1276857.html
index 7617ba17eb68..0db7ad51ab7c 100644
--- a/accessible/tests/mochitest/treeupdate/test_bug1276857.html
+++ b/accessible/tests/mochitest/treeupdate/test_bug1276857.html
@@ -112,7 +112,7 @@
     SimpleTest.waitForExplicitFinish();
     SpecialPowers.pushPrefEnv({
       set: [
-        ["dom.webcomponents.enabled", true]
+        ["dom.webcomponents.shadowdom.enabled", true]
       ]
     }, function() {
       // This test loads in an iframe, to ensure that the element instance is
diff --git a/devtools/client/inspector/markup/test/browser_markup_anonymous_03.js b/devtools/client/inspector/markup/test/browser_markup_anonymous_03.js
index 010ce06e071a..40c089802968 100644
--- a/devtools/client/inspector/markup/test/browser_markup_anonymous_03.js
+++ b/devtools/client/inspector/markup/test/browser_markup_anonymous_03.js
@@ -10,7 +10,7 @@
 const TEST_URL = URL_ROOT + "doc_markup_anonymous.html";
 
 add_task(function* () {
-  Services.prefs.setBoolPref("dom.webcomponents.enabled", true);
+  Services.prefs.setBoolPref("dom.webcomponents.shadowdom.enabled", true);
 
   let {inspector} = yield openInspectorForURL(TEST_URL);
 
diff --git a/devtools/client/inspector/markup/test/head.js b/devtools/client/inspector/markup/test/head.js
index 74efaa12fd30..78a777fa65db 100644
--- a/devtools/client/inspector/markup/test/head.js
+++ b/devtools/client/inspector/markup/test/head.js
@@ -35,7 +35,7 @@ registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.inspector.htmlPanelOpen");
   Services.prefs.clearUserPref("devtools.inspector.sidebarOpen");
   Services.prefs.clearUserPref("devtools.markup.pagesize");
-  Services.prefs.clearUserPref("dom.webcomponents.enabled");
+  Services.prefs.clearUserPref("dom.webcomponents.shadowdom.enabled");
   Services.prefs.clearUserPref("devtools.inspector.showAllAnonymousContent");
 });
 
diff --git a/devtools/client/webide/content/runtimedetails.js b/devtools/client/webide/content/runtimedetails.js
index 2e696027b6c3..35884c9b1368 100644
--- a/devtools/client/webide/content/runtimedetails.js
+++ b/devtools/client/webide/content/runtimedetails.js
@@ -140,7 +140,7 @@ function EnableCertApps() {
     "echo 'user_pref(\"devtools.debugger.forbid-certified-apps\", false);' >> prefs.js && " +
     "echo 'user_pref(\"dom.apps.developer_mode\", true);' >> prefs.js && " +
     "echo 'user_pref(\"network.disable.ipc.security\", true);' >> prefs.js && " +
-    "echo 'user_pref(\"dom.webcomponents.enabled\", true);' >> prefs.js && " +
+    "echo 'user_pref(\"dom.webcomponents.shadowdom.enabled\", true);' >> prefs.js && " +
     "start b2g"
   );
 }
diff --git a/devtools/server/tests/mochitest/test_inspector-anonymous.html b/devtools/server/tests/mochitest/test_inspector-anonymous.html
index c98ed9d9df2e..9a8ef6bf5f06 100644
--- a/devtools/server/tests/mochitest/test_inspector-anonymous.html
+++ b/devtools/server/tests/mochitest/test_inspector-anonymous.html
@@ -25,7 +25,7 @@ window.onload = function () {
   const isStylo = SpecialPowers.DOMWindowUtils.isStyledByServo;
 
   SpecialPowers.pushPrefEnv({"set": [
-    ["dom.webcomponents.enabled", true]
+    ["dom.webcomponents.shadowdom.enabled", true]
   ]});
   SimpleTest.waitForExplicitFinish();
 
diff --git a/dom/base/ChildIterator.cpp b/dom/base/ChildIterator.cpp
index 38ee89b6a360..32171fde04ff 100644
--- a/dom/base/ChildIterator.cpp
+++ b/dom/base/ChildIterator.cpp
@@ -25,7 +25,7 @@ ExplicitChildIterator::ExplicitChildIterator(const nsIContent* aParent,
     mIsFirst(aStartAtBeginning),
     mIndexInInserted(0)
 {
-  mParentAsSlot = nsDocument::IsWebComponentsEnabled(mParent) ?
+  mParentAsSlot = nsDocument::IsShadowDOMEnabled(mParent) ?
     HTMLSlotElement::FromContent(mParent) : nullptr;
 }
 
diff --git a/dom/base/DocumentOrShadowRoot.cpp b/dom/base/DocumentOrShadowRoot.cpp
index 24ff4213f235..f20b9dc4f74e 100644
--- a/dom/base/DocumentOrShadowRoot.cpp
+++ b/dom/base/DocumentOrShadowRoot.cpp
@@ -116,7 +116,7 @@ DocumentOrShadowRoot::GetRetargetedFocusedElement()
       }
 
       if (focusedContent) {
-        if (!nsDocument::IsWebComponentsEnabled(focusedContent)) {
+        if (!nsDocument::IsShadowDOMEnabled(focusedContent)) {
           return focusedContent->AsElement();
         }
 
diff --git a/dom/base/crashtests/1324463.html b/dom/base/crashtests/1324463.html
index a90358f37731..02b2a715d180 100644
--- a/dom/base/crashtests/1324463.html
+++ b/dom/base/crashtests/1324463.html
@@ -1,7 +1,7 @@
 <!DOCTYPE html>
 <html>
 <script>
-// requires: user_pref("dom.webcomponents.enabled", true);
+// requires: user_pref("dom.webcomponents.shadowdom.enabled", true);
 addEventListener("DOMContentLoaded", function(){
   let o_0 = document.createElement("span").createShadowRoot();
   let o_1 = document.createElementNS("http://www.mozilla.org/xbl", "binding");
diff --git a/dom/base/crashtests/1422931.html b/dom/base/crashtests/1422931.html
index 9f09f41efdbd..3b2dae2c36d4 100644
--- a/dom/base/crashtests/1422931.html
+++ b/dom/base/crashtests/1422931.html
@@ -1,6 +1,6 @@
 <!DOCTYPE html>
 <html>
 <body>
-<!-- Testing slot element with "dom.webcomponents.enabled" set to false -->
+<!-- Testing slot element with "dom.webcomponents.shadowdom.enabled" set to false -->
 <slot><div></div></slot>
 </html>
diff --git a/dom/base/crashtests/crashtests.list b/dom/base/crashtests/crashtests.list
index f7de5ae62b01..196745f02da1 100644
--- a/dom/base/crashtests/crashtests.list
+++ b/dom/base/crashtests/crashtests.list
@@ -194,17 +194,17 @@ load 930250.html
 load 942979.html
 load 973401.html
 load 978646.html
-pref(dom.webcomponents.enabled,true) load 1024428-1.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1024428-1.html
 load 1026714.html
-pref(dom.webcomponents.enabled,true) load 1027461-1.html
-pref(dom.webcomponents.enabled,true) load 1029710.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1027461-1.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1029710.html
 load 1154598.xhtml
 load 1157995.html
 load 1158412.html
 load 1181619.html
 load 1230422.html
 load 1251361.html
-pref(dom.webcomponents.enabled,true) load 1281715.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1281715.html
 load 1304437.html
 pref(dom.IntersectionObserver.enabled,true) load 1324209.html
 load 1324500.html
@@ -233,10 +233,10 @@ load 1400701.html
 load 1403377.html
 load 1405771.html
 load 1406109-1.html
-pref(dom.webcomponents.enabled,true) load 1324463.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1324463.html
 pref(dom.webcomponents.customelements.enabled,true) load 1413815.html
 load 1411473.html
-pref(dom.webcomponents.enabled,false) load 1422931.html
-pref(dom.webcomponents.enabled,true) load 1419799.html
+pref(dom.webcomponents.shadowdom.enabled,false) load 1422931.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1419799.html
 skip-if(!browserIsRemote) pref(dom.webcomponents.customelements.enabled,true) pref(dom.disable_open_during_load,false) load 1419902.html # skip on non e10s loads, Bug 1419902
-pref(dom.webcomponents.enabled,true) load 1428053.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1428053.html
diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index d98963c3103a..f52e2d0a93a4 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -293,7 +293,7 @@ bool nsContentUtils::sIsPerformanceTimingEnabled = false;
 bool nsContentUtils::sIsResourceTimingEnabled = false;
 bool nsContentUtils::sIsPerformanceNavigationTimingEnabled = false;
 bool nsContentUtils::sIsFormAutofillAutocompleteEnabled = false;
-bool nsContentUtils::sIsWebComponentsEnabled = false;
+bool nsContentUtils::sIsShadowDOMEnabled = false;
 bool nsContentUtils::sIsCustomElementsEnabled = false;
 bool nsContentUtils::sSendPerformanceTimingNotifications = false;
 bool nsContentUtils::sUseActivityCursor = false;
@@ -653,8 +653,8 @@ nsContentUtils::Init()
   Preferences::AddBoolVarCache(&sIsFormAutofillAutocompleteEnabled,
                                "dom.forms.autocomplete.formautofill", false);
 
-  Preferences::AddBoolVarCache(&sIsWebComponentsEnabled,
-                               "dom.webcomponents.enabled", false);
+  Preferences::AddBoolVarCache(&sIsShadowDOMEnabled,
+                               "dom.webcomponents.shadowdom.enabled", false);
 
   Preferences::AddBoolVarCache(&sIsCustomElementsEnabled,
                                "dom.webcomponents.customelements.enabled", false);
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index 7408eae4cc5e..73c2a71e1397 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -3093,7 +3093,7 @@ public:
                                     JS::MutableHandle<JS::Value> aValue);
 
   static bool
-  IsWebComponentsEnabled() { return sIsWebComponentsEnabled; }
+  IsShadowDOMEnabled() { return sIsShadowDOMEnabled; }
 
   /**
    * Returns true if reserved key events should be prevented from being sent
@@ -3395,7 +3395,7 @@ private:
   static bool sIsPerformanceNavigationTimingEnabled;
   static bool sIsFrameTimingPrefEnabled;
   static bool sIsFormAutofillAutocompleteEnabled;
-  static bool sIsWebComponentsEnabled;
+  static bool sIsShadowDOMEnabled;
   static bool sIsCustomElementsEnabled;
   static bool sSendPerformanceTimingNotifications;
   static bool sUseActivityCursor;
diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index f8b129b12c86..4ed4da2de622 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -1526,7 +1526,7 @@ nsIDocument::nsIDocument()
 
   // Set this when document is created and value stays the same for the lifetime
   // of the document.
-  mIsWebComponentsEnabled = nsContentUtils::IsWebComponentsEnabled();
+  mIsShadowDOMEnabled = nsContentUtils::IsShadowDOMEnabled();
 }
 
 nsDocument::nsDocument(const char* aContentType)
@@ -2668,7 +2668,7 @@ nsDocument::IsSynthesized() {
 }
 
 bool
-nsDocument::IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject)
+nsDocument::IsShadowDOMEnabled(JSContext* aCx, JSObject* aObject)
 {
   JS::Rooted<JSObject*> obj(aCx, aObject);
 
@@ -2682,13 +2682,13 @@ nsDocument::IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject)
     return false;
   }
 
-  return doc->IsWebComponentsEnabled();
+  return doc->IsShadowDOMEnabled();
 }
 
 bool
-nsDocument::IsWebComponentsEnabled(const nsINode* aNode)
+nsDocument::IsShadowDOMEnabled(const nsINode* aNode)
 {
-  return aNode->OwnerDoc()->IsWebComponentsEnabled();
+  return aNode->OwnerDoc()->IsShadowDOMEnabled();
 }
 
 nsresult
diff --git a/dom/base/nsDocument.h b/dom/base/nsDocument.h
index ee6bad8b997f..6e1b423ff42d 100644
--- a/dom/base/nsDocument.h
+++ b/dom/base/nsDocument.h
@@ -626,11 +626,10 @@ public:
   virtual void ResolveScheduledSVGPresAttrs() override;
   bool IsSynthesized();
 
-  // Check whether web components are enabled for the global of aObject.
-  static bool IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject);
-  // Check whether web components are enabled for the document this node belongs
-  // to.
-  static bool IsWebComponentsEnabled(const nsINode* aNode);
+  // Check whether shadow DOM is enabled for the global of aObject.
+  static bool IsShadowDOMEnabled(JSContext* aCx, JSObject* aObject);
+  // Check whether shadow DOM is enabled for the document this node belongs to.
+  static bool IsShadowDOMEnabled(const nsINode* aNode);
 private:
   void AddOnDemandBuiltInUASheet(mozilla::StyleSheet* aSheet);
   void SendToConsole(nsCOMArray<nsISecurityConsoleMessage>& aMessages);
diff --git a/dom/base/nsIDocument.h b/dom/base/nsIDocument.h
index ce3c8afd8a9d..f3c47ab2e454 100644
--- a/dom/base/nsIDocument.h
+++ b/dom/base/nsIDocument.h
@@ -3178,9 +3178,9 @@ public:
   virtual bool AllowPaymentRequest() const = 0;
   virtual void SetAllowPaymentRequest(bool aAllowPaymentRequest) = 0;
 
-  bool IsWebComponentsEnabled() const
+  bool IsShadowDOMEnabled() const
   {
-    return mIsWebComponentsEnabled;
+    return mIsShadowDOMEnabled;
   }
 
   bool ModuleScriptsEnabled();
@@ -3538,8 +3538,9 @@ protected:
   // True if the encoding menu should be disabled.
   bool mEncodingMenuDisabled : 1;
 
-  // True if dom.webcomponents.enabled pref is set when document is created.
-  bool mIsWebComponentsEnabled : 1;
+  // True if dom.webcomponents.shadowdom.enabled pref is set when document is
+  // created.
+  bool mIsShadowDOMEnabled : 1;
 
   // Whether <style scoped> support is enabled in this document.
   enum { eScopedStyle_Unknown, eScopedStyle_Disabled, eScopedStyle_Enabled };
diff --git a/dom/base/nsTextNode.cpp b/dom/base/nsTextNode.cpp
index ce3ea3c68797..c3b406339829 100644
--- a/dom/base/nsTextNode.cpp
+++ b/dom/base/nsTextNode.cpp
@@ -159,9 +159,9 @@ void nsTextNode::UnbindFromTree(bool aDeep, bool aNullParent)
 }
 
 bool
-nsTextNode::IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject)
+nsTextNode::IsShadowDOMEnabled(JSContext* aCx, JSObject* aObject)
 {
-  return nsDocument::IsWebComponentsEnabled(aCx, aObject);
+  return nsDocument::IsShadowDOMEnabled(aCx, aObject);
 }
 
 #ifdef DEBUG
diff --git a/dom/base/nsTextNode.h b/dom/base/nsTextNode.h
index 94b8dbd1d778..0e1f7b49d0c3 100644
--- a/dom/base/nsTextNode.h
+++ b/dom/base/nsTextNode.h
@@ -77,7 +77,7 @@ public:
 
   // Need to have a copy here because including nsDocument.h in this file will
   // fail to build on Windows.
-  static bool IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject);
+  static bool IsShadowDOMEnabled(JSContext* aCx, JSObject* aObject);
 
 #ifdef DEBUG
   virtual void List(FILE* out, int32_t aIndent) const override;
diff --git a/dom/base/test/test_bug1025933.html b/dom/base/test/test_bug1025933.html
index 4f8f87e07a63..b8fbab28d5c7 100644
--- a/dom/base/test/test_bug1025933.html
+++ b/dom/base/test/test_bug1025933.html
@@ -17,7 +17,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1025933
   function test() {
     SpecialPowers.pushPrefEnv({
       set: [
-        ["dom.webcomponents.enabled", true]
+        ["dom.webcomponents.shadowdom.enabled", true]
       ]
     }, function() {
       var iframe = document.createElement('iframe');
diff --git a/dom/base/test/test_bug1037687.html b/dom/base/test/test_bug1037687.html
index 3ff96d5b51a4..367f38cdc9f7 100644
--- a/dom/base/test/test_bug1037687.html
+++ b/dom/base/test/test_bug1037687.html
@@ -22,7 +22,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1037687
   SimpleTest.waitForExplicitFinish();
   SpecialPowers.pushPrefEnv({
     set: [
-      ["dom.webcomponents.enabled", true]
+      ["dom.webcomponents.shadowdom.enabled", true]
     ]
   }, function() {
     // This test loads in an iframe, to ensure that the element instance is
diff --git a/dom/events/test/test_bug1079236.html b/dom/events/test/test_bug1079236.html
index b13cdc19b3b0..cca3d2eaf1b3 100644
--- a/dom/events/test/test_bug1079236.html
+++ b/dom/events/test/test_bug1079236.html
@@ -51,7 +51,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1079236
   SimpleTest.waitForFocus(() => {
     SpecialPowers.pushPrefEnv({
       set: [
-        ["dom.webcomponents.enabled", true]
+        ["dom.webcomponents.shadowdom.enabled", true]
       ]
     }, runTests);
   });
diff --git a/dom/events/test/test_bug1145910.html b/dom/events/test/test_bug1145910.html
index 2dec7eeb22d9..0154febb8eea 100644
--- a/dom/events/test/test_bug1145910.html
+++ b/dom/events/test/test_bug1145910.html
@@ -48,7 +48,7 @@ SimpleTest.waitForExplicitFinish();
 SimpleTest.waitForFocus(() => {
   SpecialPowers.pushPrefEnv({
     set: [
-      ["dom.webcomponents.enabled", true]
+      ["dom.webcomponents.shadowdom.enabled", true]
     ]
   }, runTests);
 });
diff --git a/dom/events/test/test_bug1150308.html b/dom/events/test/test_bug1150308.html
index f1392cd3fbf1..d82c441a73d6 100644
--- a/dom/events/test/test_bug1150308.html
+++ b/dom/events/test/test_bug1150308.html
@@ -44,7 +44,7 @@ SimpleTest.waitForExplicitFinish();
 SimpleTest.waitForFocus(() => {
   SpecialPowers.pushPrefEnv({
     set: [
-      ["dom.webcomponents.enabled", true]
+      ["dom.webcomponents.shadowdom.enabled", true]
     ]
   }, runTests);
 });
diff --git a/dom/events/test/test_bug1264380.html b/dom/events/test/test_bug1264380.html
index f5814394be3e..8c166ae4c731 100644
--- a/dom/events/test/test_bug1264380.html
+++ b/dom/events/test/test_bug1264380.html
@@ -52,7 +52,7 @@ SimpleTest.waitForExplicitFinish();
 SimpleTest.waitForFocus(() => {
   SpecialPowers.pushPrefEnv({
     set: [
-      ["dom.webcomponents.enabled", true]
+      ["dom.webcomponents.shadowdom.enabled", true]
     ]
   }, runTests);
 });
diff --git a/dom/html/HTMLSlotElement.cpp b/dom/html/HTMLSlotElement.cpp
index bb9cb3cff5e0..ec9aa2be5ec3 100644
--- a/dom/html/HTMLSlotElement.cpp
+++ b/dom/html/HTMLSlotElement.cpp
@@ -17,7 +17,7 @@ NS_NewHTMLSlotElement(already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
                       mozilla::dom::FromParser aFromParser)
 {
   RefPtr<mozilla::dom::NodeInfo> nodeInfo(aNodeInfo);
-  if (nsDocument::IsWebComponentsEnabled(nodeInfo->GetDocument())) {
+  if (nsDocument::IsShadowDOMEnabled(nodeInfo->GetDocument())) {
     already_AddRefed<mozilla::dom::NodeInfo> nodeInfoArg(nodeInfo.forget());
     return new mozilla::dom::HTMLSlotElement(nodeInfoArg);
   }
diff --git a/dom/ipc/ContentPrefs.cpp b/dom/ipc/ContentPrefs.cpp
index 6468cc7efc4a..9af730e9c623 100644
--- a/dom/ipc/ContentPrefs.cpp
+++ b/dom/ipc/ContentPrefs.cpp
@@ -82,7 +82,7 @@ const char* mozilla::dom::ContentPrefs::gEarlyPrefs[] = {
   "dom.vibrator.max_vibrate_list_len",
   "dom.vibrator.max_vibrate_ms",
   "dom.webcomponents.customelements.enabled",
-  "dom.webcomponents.enabled",
+  "dom.webcomponents.shadowdom.enabled",
   "focusmanager.testmode",
   "font.size.inflation.disabledInMasterProcess",
   "font.size.inflation.emPerLine",
diff --git a/dom/tests/mochitest/webcomponents/head.js b/dom/tests/mochitest/webcomponents/head.js
index 21597711a2dd..5cec7f937334 100644
--- a/dom/tests/mochitest/webcomponents/head.js
+++ b/dom/tests/mochitest/webcomponents/head.js
@@ -5,17 +5,17 @@
 "use strict";
 
 /**
- * Set dom.webcomponents.enabled pref to true and loads an iframe, to ensure
- * that the Element instance is loaded with the correct value of the
+ * Set dom.webcomponents.shadowdom.enabled pref to true and loads an iframe, to
+ * ensure that the Element instance is loaded with the correct value of the
  * preference.
  *
  * @return {Promise} promise that resolves when iframe is loaded.
  */
-function setWebComponentsPrefAndCreateIframe(aSrcDoc) {
+function setShadowDOMPrefAndCreateIframe(aSrcDoc) {
   return new Promise(function (aResolve, aReject) {
     SpecialPowers.pushPrefEnv({
       set: [
-        ["dom.webcomponents.enabled", true]
+        ["dom.webcomponents.shadowdom.enabled", true]
       ]
     }, () => {
       let iframe = document.createElement("iframe");
diff --git a/dom/tests/mochitest/webcomponents/test_bug1269155.html b/dom/tests/mochitest/webcomponents/test_bug1269155.html
index d1adcee62073..c95686108e24 100644
--- a/dom/tests/mochitest/webcomponents/test_bug1269155.html
+++ b/dom/tests/mochitest/webcomponents/test_bug1269155.html
@@ -22,7 +22,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1269155
 SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="content" style="display: none"> </div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     var host = aDocument.querySelector('#content');
     var root = host.attachShadow({mode: "open"});
diff --git a/dom/tests/mochitest/webcomponents/test_custom_element_in_shadow.html b/dom/tests/mochitest/webcomponents/test_custom_element_in_shadow.html
index 4c820ba1be1e..2b3102f3896b 100644
--- a/dom/tests/mochitest/webcomponents/test_custom_element_in_shadow.html
+++ b/dom/tests/mochitest/webcomponents/test_custom_element_in_shadow.html
@@ -17,7 +17,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1087460
 SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="container"></div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
 
     // Test callback for custom element when used after registration.
diff --git a/dom/tests/mochitest/webcomponents/test_detached_style.html b/dom/tests/mochitest/webcomponents/test_detached_style.html
index 075e5ec1f473..f4f7477617f6 100644
--- a/dom/tests/mochitest/webcomponents/test_detached_style.html
+++ b/dom/tests/mochitest/webcomponents/test_detached_style.html
@@ -16,7 +16,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1062578
 SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="grabme"></div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     var host = aDocument.createElement("div");
     var shadow = host.attachShadow({mode: "open"});
diff --git a/dom/tests/mochitest/webcomponents/test_document_adoptnode.html b/dom/tests/mochitest/webcomponents/test_document_adoptnode.html
index 6796427cf623..59d75c3e633b 100644
--- a/dom/tests/mochitest/webcomponents/test_document_adoptnode.html
+++ b/dom/tests/mochitest/webcomponents/test_document_adoptnode.html
@@ -20,7 +20,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1177991
 <script class="testbody" type="text/javascript">
 
 SimpleTest.waitForExplicitFinish();
-setWebComponentsPrefAndCreateIframe()
+setShadowDOMPrefAndCreateIframe()
   .then((aDocument) => {
     var thrownException = false;
     var shadowRoot = aDocument.createElement('div').attachShadow({mode: "open"});
diff --git a/dom/tests/mochitest/webcomponents/test_document_importnode.html b/dom/tests/mochitest/webcomponents/test_document_importnode.html
index 6519d25d2625..d5a175edecc6 100644
--- a/dom/tests/mochitest/webcomponents/test_document_importnode.html
+++ b/dom/tests/mochitest/webcomponents/test_document_importnode.html
@@ -20,7 +20,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1177914
 <script class="testbody" type="text/javascript">
 
 SimpleTest.waitForExplicitFinish();
-setWebComponentsPrefAndCreateIframe()
+setShadowDOMPrefAndCreateIframe()
   .then((aDocument) => {
     var thrownException = false;
     var shadowRoot = aDocument.createElement('div').attachShadow({mode: "open"});
diff --git a/dom/tests/mochitest/webcomponents/test_event_retarget.html b/dom/tests/mochitest/webcomponents/test_event_retarget.html
index d82531b8caae..773c87fe077e 100644
--- a/dom/tests/mochitest/webcomponents/test_event_retarget.html
+++ b/dom/tests/mochitest/webcomponents/test_event_retarget.html
@@ -14,7 +14,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=887541
 <script>
 
 SimpleTest.waitForExplicitFinish();
-setWebComponentsPrefAndCreateIframe()
+setShadowDOMPrefAndCreateIframe()
   .then((aDocument) => {
     /*
      * Creates an event listener with an expected event target.
diff --git a/dom/tests/mochitest/webcomponents/test_event_stopping.html b/dom/tests/mochitest/webcomponents/test_event_stopping.html
index b38729e1b23d..7c0402085c05 100644
--- a/dom/tests/mochitest/webcomponents/test_event_stopping.html
+++ b/dom/tests/mochitest/webcomponents/test_event_stopping.html
@@ -17,7 +17,7 @@ var els = SpecialPowers.Cc["@mozilla.org/eventlistenerservice;1"]
             .getService(SpecialPowers.Ci.nsIEventListenerService);
 
 SimpleTest.waitForExplicitFinish();
-setWebComponentsPrefAndCreateIframe()
+setShadowDOMPrefAndCreateIframe()
   .then((aDocument) => {
     function eventListener(e) {
       eventChain.push(this);
diff --git a/dom/tests/mochitest/webcomponents/test_shadowroot.html b/dom/tests/mochitest/webcomponents/test_shadowroot.html
index a30cd59ad4e4..2e94f3f9b6e8 100644
--- a/dom/tests/mochitest/webcomponents/test_shadowroot.html
+++ b/dom/tests/mochitest/webcomponents/test_shadowroot.html
@@ -17,7 +17,7 @@ SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="movedtoshadow" class="testclass"></div>' +
               '<svg id="svgmovedtoshadow"></svg>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     // Create ShadowRoot.
     var element = aDocument.createElement("div");
diff --git a/dom/tests/mochitest/webcomponents/test_shadowroot_clonenode.html b/dom/tests/mochitest/webcomponents/test_shadowroot_clonenode.html
index 15f272e3bc0c..a9190ad67a4a 100644
--- a/dom/tests/mochitest/webcomponents/test_shadowroot_clonenode.html
+++ b/dom/tests/mochitest/webcomponents/test_shadowroot_clonenode.html
@@ -22,7 +22,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=1429982
 
 /** Test for Bug 1429982 **/
 SimpleTest.waitForExplicitFinish();
-setWebComponentsPrefAndCreateIframe()
+setShadowDOMPrefAndCreateIframe()
   .then((aDocument) => {
     var element = aDocument.createElement("div");
     var shadowRoot = element.attachShadow({mode: "open"});
diff --git a/dom/tests/mochitest/webcomponents/test_shadowroot_inert_element.html b/dom/tests/mochitest/webcomponents/test_shadowroot_inert_element.html
index 4ff6eff671a9..5a48f563049c 100644
--- a/dom/tests/mochitest/webcomponents/test_shadowroot_inert_element.html
+++ b/dom/tests/mochitest/webcomponents/test_shadowroot_inert_element.html
@@ -16,7 +16,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=806506
 SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="grabme"></div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     function runChecks() {
       isnot(aDocument.defaultView.getComputedStyle(shadowSpan, null).getPropertyValue("padding-top"), "10px", "Link element should be inert.");
diff --git a/dom/tests/mochitest/webcomponents/test_shadowroot_style.html b/dom/tests/mochitest/webcomponents/test_shadowroot_style.html
index bf89b454339e..121c47d892f6 100644
--- a/dom/tests/mochitest/webcomponents/test_shadowroot_style.html
+++ b/dom/tests/mochitest/webcomponents/test_shadowroot_style.html
@@ -21,7 +21,7 @@ SimpleTest.waitForExplicitFinish();
 
 var content = '<div class="tall" id="bodydiv"></div>' +
               '<div id="container"></div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     var iframeWin = aDocument.defaultView;
 
diff --git a/dom/tests/mochitest/webcomponents/test_shadowroot_style_order.html b/dom/tests/mochitest/webcomponents/test_shadowroot_style_order.html
index 9262b534f44f..188b00380f01 100644
--- a/dom/tests/mochitest/webcomponents/test_shadowroot_style_order.html
+++ b/dom/tests/mochitest/webcomponents/test_shadowroot_style_order.html
@@ -16,7 +16,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=806506
 SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="container"></div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     var iframeWin = aDocument.defaultView;
 
diff --git a/dom/tests/mochitest/webcomponents/test_style_fallback_content.html b/dom/tests/mochitest/webcomponents/test_style_fallback_content.html
index fb71e2ebe370..d7e07c6edc36 100644
--- a/dom/tests/mochitest/webcomponents/test_style_fallback_content.html
+++ b/dom/tests/mochitest/webcomponents/test_style_fallback_content.html
@@ -16,7 +16,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=806506
 SimpleTest.waitForExplicitFinish();
 
 var content = '<div id="grabme"></div>';
-setWebComponentsPrefAndCreateIframe(content)
+setShadowDOMPrefAndCreateIframe(content)
   .then((aDocument) => {
     var iframeWin = aDocument.defaultView;
 
diff --git a/dom/webidl/Element.webidl b/dom/webidl/Element.webidl
index ad75312b2bfa..75a15383c3f0 100644
--- a/dom/webidl/Element.webidl
+++ b/dom/webidl/Element.webidl
@@ -254,17 +254,17 @@ dictionary ShadowRootInit {
 // https://dom.spec.whatwg.org/#element
 partial interface Element {
   // Shadow DOM v1
-  [Throws, Func="nsDocument::IsWebComponentsEnabled"]
+  [Throws, Func="nsDocument::IsShadowDOMEnabled"]
   ShadowRoot attachShadow(ShadowRootInit shadowRootInitDict);
-  [BinaryName="shadowRootByMode", Func="nsDocument::IsWebComponentsEnabled"]
+  [BinaryName="shadowRootByMode", Func="nsDocument::IsShadowDOMEnabled"]
   readonly attribute ShadowRoot? shadowRoot;
-  [BinaryName="assignedSlotByMode", Func="nsDocument::IsWebComponentsEnabled"]
+  [BinaryName="assignedSlotByMode", Func="nsDocument::IsShadowDOMEnabled"]
   readonly attribute HTMLSlotElement? assignedSlot;
-  [CEReactions, Unscopable, SetterThrows, Func="nsDocument::IsWebComponentsEnabled"]
+  [CEReactions, Unscopable, SetterThrows, Func="nsDocument::IsShadowDOMEnabled"]
            attribute DOMString slot;
 
   // [deprecated] Shadow DOM v0
-  [Throws, Func="nsDocument::IsWebComponentsEnabled"]
+  [Throws, Func="nsDocument::IsShadowDOMEnabled"]
   ShadowRoot createShadowRoot();
 };
 
diff --git a/dom/webidl/HTMLSlotElement.webidl b/dom/webidl/HTMLSlotElement.webidl
index 604d31ddee1f..c4a4f6b13d6e 100644
--- a/dom/webidl/HTMLSlotElement.webidl
+++ b/dom/webidl/HTMLSlotElement.webidl
@@ -11,7 +11,7 @@
  * and create derivative works of this document.
  */
 
-[Func="nsDocument::IsWebComponentsEnabled", Exposed=Window, HTMLConstructor]
+[Func="nsDocument::IsShadowDOMEnabled", Exposed=Window, HTMLConstructor]
 interface HTMLSlotElement : HTMLElement {
   [CEReactions, SetterThrows] attribute DOMString name;
   sequence<Node> assignedNodes(optional AssignedNodesOptions options);
diff --git a/dom/webidl/ShadowRoot.webidl b/dom/webidl/ShadowRoot.webidl
index 81b50e58bde9..33e1c0f5538b 100644
--- a/dom/webidl/ShadowRoot.webidl
+++ b/dom/webidl/ShadowRoot.webidl
@@ -17,7 +17,7 @@ enum ShadowRootMode {
 };
 
 // https://dom.spec.whatwg.org/#shadowroot
-[Func="nsDocument::IsWebComponentsEnabled"]
+[Func="nsDocument::IsShadowDOMEnabled"]
 interface ShadowRoot : DocumentFragment
 {
   readonly attribute Element? activeElement;
diff --git a/dom/webidl/Text.webidl b/dom/webidl/Text.webidl
index fb7b5d6857f0..61041149b096 100644
--- a/dom/webidl/Text.webidl
+++ b/dom/webidl/Text.webidl
@@ -19,7 +19,7 @@ interface Text : CharacterData {
 };
 
 partial interface Text {
-  [BinaryName="assignedSlotByMode", Func="nsTextNode::IsWebComponentsEnabled"]
+  [BinaryName="assignedSlotByMode", Func="nsTextNode::IsShadowDOMEnabled"]
   readonly attribute HTMLSlotElement? assignedSlot;
 };
 
diff --git a/layout/base/crashtests/crashtests.list b/layout/base/crashtests/crashtests.list
index 6c3ff6ee111c..0bfbe4c32f23 100644
--- a/layout/base/crashtests/crashtests.list
+++ b/layout/base/crashtests/crashtests.list
@@ -475,7 +475,7 @@ load 1162813.xul
 load 1163583.html
 load 1234622-1.html
 load 1235467-1.html
-pref(dom.webcomponents.enabled,true) load 1261351.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1261351.html
 load 1270797-1.html
 load 1278455-1.html
 load 1286889.html
@@ -520,5 +520,5 @@ load 1420533.html
 load 1425959.html
 load 1425893.html
 load 1428353.html
-pref(dom.webcomponents.enabled,true) load 1429088.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1429088.html
 load 1429961.html
diff --git a/layout/generic/crashtests/crashtests.list b/layout/generic/crashtests/crashtests.list
index 9b58f6d679aa..e163fb39cc98 100644
--- a/layout/generic/crashtests/crashtests.list
+++ b/layout/generic/crashtests/crashtests.list
@@ -586,7 +586,7 @@ load 1039454-1.html
 load 1042489.html
 load 1054010-1.html
 load 1058954-1.html
-asserts-if(!stylo,0-2) pref(dom.webcomponents.enabled,true) pref(dom.webcomponents.customelements.enabled,true) load 1059138-1.html # bug 1389936
+asserts-if(!stylo,0-2) pref(dom.webcomponents.shadowdom.enabled,true) pref(dom.webcomponents.customelements.enabled,true) load 1059138-1.html # bug 1389936
 load 1134531.html
 load 1134667.html
 load 1137723-1.html
diff --git a/layout/reftests/bugs/reftest.list b/layout/reftests/bugs/reftest.list
index 8851024768f6..073ee5d8611a 100644
--- a/layout/reftests/bugs/reftest.list
+++ b/layout/reftests/bugs/reftest.list
@@ -1859,7 +1859,7 @@ pref(layout.css.moz-document.content.enabled,false) == 1035091-2.html 1035091-re
 == 1062108-1.html 1062108-1-ref.html
 == 1062792-1.html 1062792-1-ref.html
 == 1062963-floatmanager-reflow.html 1062963-floatmanager-reflow-ref.html
-test-pref(dom.webcomponents.enabled,true) == 1066554-1.html 1066554-1-ref.html
+test-pref(dom.webcomponents.shadowdom.enabled,true) == 1066554-1.html 1066554-1-ref.html
 == 1069716-1.html 1069716-1-ref.html
 == 1078262-1.html about:blank
 test-pref(layout.testing.overlay-scrollbars.always-visible,false) == 1081072-1.html 1081072-1-ref.html
diff --git a/layout/reftests/css-display/reftest.list b/layout/reftests/css-display/reftest.list
index 9f8dd70bda71..ab7a99e5c052 100644
--- a/layout/reftests/css-display/reftest.list
+++ b/layout/reftests/css-display/reftest.list
@@ -17,7 +17,7 @@ fuzzy-if(winWidget,12,100) == display-contents-style-inheritance-1-dom-mutations
 == display-contents-visibility-hidden-2.html display-contents-visibility-hidden-ref.html
 == display-contents-495385-2d.html display-contents-495385-2d-ref.html
 fuzzy-if(Android,7,3935) == display-contents-xbl.xhtml display-contents-xbl-ref.html
-#bug 1421540 fuzzy-if(Android,7,1186) pref(dom.webcomponents.enabled,true) == display-contents-shadow-dom-1.html display-contents-shadow-dom-1-ref.html
+#bug 1421540 fuzzy-if(Android,7,1186) pref(dom.webcomponents.shadowdom.enabled,true) == display-contents-shadow-dom-1.html display-contents-shadow-dom-1-ref.html
 == display-contents-xbl-2.xul display-contents-xbl-2-ref.xul
 == display-contents-xbl-3.xul display-contents-xbl-3-ref.xul
 skip == display-contents-xbl-4.xul display-contents-xbl-4-ref.xul # fails (not just asserts) due to bug 1089223
diff --git a/layout/reftests/forms/legend/reftest.list b/layout/reftests/forms/legend/reftest.list
index 50519afa4b30..af849cbf9b81 100644
--- a/layout/reftests/forms/legend/reftest.list
+++ b/layout/reftests/forms/legend/reftest.list
@@ -1,4 +1,4 @@
 == legend.html legend-ref.html
-#bug 1418002 fuzzy-if(skiaContent,1,7) pref(dom.webcomponents.enabled,true) == shadow-dom.html shadow-dom-ref.html
+#bug 1418002 fuzzy-if(skiaContent,1,7) pref(dom.webcomponents.shadowdom.enabled,true) == shadow-dom.html shadow-dom-ref.html
 == 1273433.html 1273433-ref.html
 fails-if(styloVsGecko||stylo) == 1339287.html 1339287-ref.html
diff --git a/layout/reftests/mathml/reftest.list b/layout/reftests/mathml/reftest.list
index c733b04b47b6..f89069448624 100644
--- a/layout/reftests/mathml/reftest.list
+++ b/layout/reftests/mathml/reftest.list
@@ -367,7 +367,7 @@ fuzzy-if(OSX,1,100) fuzzy-if(skiaContent,1,14) == mfrac-D-1.html mfrac-D-1-ref.h
 == mfrac-D-3.html mfrac-D-3-ref.html
 == mfrac-D-4.html mfrac-D-4-ref.html
 == mfrac-E-1.html mfrac-E-1-ref.html
-test-pref(dom.webcomponents.enabled,true) == shadow-dom-1.html shadow-dom-1-ref.html
+test-pref(dom.webcomponents.shadowdom.enabled,true) == shadow-dom-1.html shadow-dom-1-ref.html
 pref(dom.meta-viewport.enabled,true) pref(font.size.inflation.emPerLine,25) == font-inflation-1.html font-inflation-1-ref.html
 test-pref(font.minimum-size.x-math,40) == default-font.html default-font-ref.html
 != radicalbar-1.html about:blank
diff --git a/layout/reftests/webcomponents/reftest.list b/layout/reftests/webcomponents/reftest.list
index 5c2d772b9729..18925f984aab 100644
--- a/layout/reftests/webcomponents/reftest.list
+++ b/layout/reftests/webcomponents/reftest.list
@@ -1,23 +1,23 @@
-pref(dom.webcomponents.enabled,true) == cross-tree-selection-1.html cross-tree-selection-1-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-1.html basic-shadow-1-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-2.html basic-shadow-2-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-3.html basic-shadow-3-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-4.html basic-shadow-4-ref.html
-pref(dom.webcomponents.enabled,true) == fallback-content-1.html fallback-content-1-ref.html
-pref(dom.webcomponents.enabled,true) == remove-insertion-point-1.html remove-insertion-point-1-ref.html
-pref(dom.webcomponents.enabled,true) == nested-insertion-point-1.html nested-insertion-point-1-ref.html
-pref(dom.webcomponents.enabled,true) == update-dist-node-descendants-1.html update-dist-node-descendants-1-ref.html
-pref(dom.webcomponents.enabled,true) fuzzy-if(Android,2,7) == input-transition-1.html input-transition-1-ref.html
-pref(dom.webcomponents.enabled,true) == dynamic-insertion-point-distribution-1.html dynamic-insertion-point-distribution-1-ref.html
-pref(dom.webcomponents.enabled,true) == dynamic-insertion-point-distribution-2.html dynamic-insertion-point-distribution-2-ref.html
-pref(dom.webcomponents.enabled,true) == remove-append-shadow-host-1.html remove-append-shadow-host-1-ref.html
-pref(dom.webcomponents.enabled,true) == reframe-shadow-child-1.html reframe-shadow-child-ref.html
-pref(dom.webcomponents.enabled,true) == reframe-shadow-child-2.html reframe-shadow-child-ref.html
-pref(dom.webcomponents.enabled,true) == style-sharing.html style-sharing-ref.html
-pref(dom.webcomponents.enabled,true) skip-if(!stylo||styloVsGecko) == style-sharing-across-shadow.html style-sharing-ref.html # bug 1412400
-pref(dom.webcomponents.enabled,true) == basic-slot-1.html basic-slot-1-ref.html
-pref(dom.webcomponents.enabled,true) == basic-slot-2.html basic-slot-2-ref.html
-pref(dom.webcomponents.enabled,true) == basic-slot-3.html basic-slot-3-ref.html
-pref(dom.webcomponents.enabled,true) == basic-slot-4.html basic-slot-3-ref.html
-pref(dom.webcomponents.enabled,true) == basic-slot-5.html basic-slot-5-ref.html
-pref(dom.webcomponents.enabled,true) == basic-slot-6.html basic-slot-6-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == cross-tree-selection-1.html cross-tree-selection-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-shadow-1.html basic-shadow-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-shadow-2.html basic-shadow-2-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-shadow-3.html basic-shadow-3-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-shadow-4.html basic-shadow-4-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == fallback-content-1.html fallback-content-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == remove-insertion-point-1.html remove-insertion-point-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == nested-insertion-point-1.html nested-insertion-point-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == update-dist-node-descendants-1.html update-dist-node-descendants-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) fuzzy-if(Android,2,7) == input-transition-1.html input-transition-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == dynamic-insertion-point-distribution-1.html dynamic-insertion-point-distribution-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == dynamic-insertion-point-distribution-2.html dynamic-insertion-point-distribution-2-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == remove-append-shadow-host-1.html remove-append-shadow-host-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == reframe-shadow-child-1.html reframe-shadow-child-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == reframe-shadow-child-2.html reframe-shadow-child-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == style-sharing.html style-sharing-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) skip-if(!stylo||styloVsGecko) == style-sharing-across-shadow.html style-sharing-ref.html # bug 1412400
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-slot-1.html basic-slot-1-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-slot-2.html basic-slot-2-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-slot-3.html basic-slot-3-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-slot-4.html basic-slot-3-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-slot-5.html basic-slot-5-ref.html
+pref(dom.webcomponents.shadowdom.enabled,true) == basic-slot-6.html basic-slot-6-ref.html
diff --git a/layout/style/crashtests/crashtests.list b/layout/style/crashtests/crashtests.list
index 2c0239e85a72..445c5602157c 100644
--- a/layout/style/crashtests/crashtests.list
+++ b/layout/style/crashtests/crashtests.list
@@ -112,12 +112,12 @@ load 945048-1.html
 load 972199-1.html
 load 989965-1.html
 load 992333-1.html
-pref(dom.webcomponents.enabled,true) load 1017798-1.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1017798-1.html
 load 1028514-1.html
 load 1066089-1.html
 load 1074651-1.html
 load 1135534.html
-pref(dom.webcomponents.enabled,true) load 1089463-1.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1089463-1.html
 pref(layout.css.expensive-style-struct-assertions.enabled,true) load 1136010-1.html
 pref(layout.css.expensive-style-struct-assertions.enabled,true) load 1146101-1.html
 load 1153693-1.html
@@ -261,9 +261,9 @@ load 1411478.html
 load 1413288.html
 load 1413361.html
 load 1415663.html
-pref(dom.webcomponents.enabled,true) load 1415353.html
-load 1415021.html # This should have dom.webcomponents.enabled=true, but it leaks the world, see bug 1416296.
+pref(dom.webcomponents.shadowdom.enabled,true) load 1415353.html
+load 1415021.html # This should have dom.webcomponents.shadowdom.enabled=true, but it leaks the world, see bug 1416296.
 load 1418059.html
 skip-if(!stylo) test-pref(dom.animations-api.core.enabled,true) load 1418867.html
-pref(dom.webcomponents.enabled,true) load 1419554.html
+pref(dom.webcomponents.shadowdom.enabled,true) load 1419554.html
 load 1426312.html
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index a5bb63c04121..3e00e24c5f0f 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1407,7 +1407,7 @@ pref("dom.event.clipboardevents.enabled",   true);
 pref("dom.event.highrestimestamp.enabled",  true);
 pref("dom.event.coalesce_mouse_move",       true);
 
-pref("dom.webcomponents.enabled",           false);
+pref("dom.webcomponents.shadowdom.enabled", false);
 #ifdef NIGHTLY_BUILD
 pref("dom.webcomponents.customelements.enabled", true);
 #else
diff --git a/testing/marionette/harness/marionette_harness/tests/unit/test_shadow_dom.py b/testing/marionette/harness/marionette_harness/tests/unit/test_shadow_dom.py
index 3f91d7cc0cbc..e218802b9436 100644
--- a/testing/marionette/harness/marionette_harness/tests/unit/test_shadow_dom.py
+++ b/testing/marionette/harness/marionette_harness/tests/unit/test_shadow_dom.py
@@ -16,7 +16,7 @@ class TestShadowDom(MarionetteTestCase):
 
     def setUp(self):
         super(TestShadowDom, self).setUp()
-        self.marionette.set_pref("dom.webcomponents.enabled", True)
+        self.marionette.set_pref("dom.webcomponents.shadowdom.enabled", True)
         self.marionette.navigate(self.marionette.absolute_url("test_shadow_dom.html"))
 
         self.host = self.marionette.find_element(By.ID, "host")
@@ -24,7 +24,7 @@ class TestShadowDom(MarionetteTestCase):
         self.button = self.marionette.find_element(By.ID, "button")
 
     def tearDown(self):
-        self.marionette.clear_pref("dom.webcomponents.enabled")
+        self.marionette.clear_pref("dom.webcomponents.shadowdom.enabled")
         super(TestShadowDom, self).tearDown()
 
     def test_chrome_error(self):
diff --git a/testing/profiles/prefs_general.js b/testing/profiles/prefs_general.js
index f47d304f22e0..46210db7a23c 100644
--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -65,7 +65,7 @@ user_pref("media.gmp-manager.updateEnabled", false);
 user_pref("media.hls.server.url", "http://%(server)s/tests/dom/media/test/hls");
 user_pref("dom.w3c_touch_events.enabled", 1);
 user_pref("layout.accessiblecaret.enabled_on_touch", false);
-user_pref("dom.webcomponents.enabled", false);
+user_pref("dom.webcomponents.shadowdom.enabled", false);
 user_pref("dom.webcomponents.customelements.enabled", true);
 // Existing tests assume there is no font size inflation.
 user_pref("font.size.inflation.emPerLine", 0);
diff --git a/testing/web-platform/meta/content-security-policy/securitypolicyviolation/targeting.html.ini b/testing/web-platform/meta/content-security-policy/securitypolicyviolation/targeting.html.ini
index db02cbe270a9..b56607de7bde 100644
--- a/testing/web-platform/meta/content-security-policy/securitypolicyviolation/targeting.html.ini
+++ b/testing/web-platform/meta/content-security-policy/securitypolicyviolation/targeting.html.ini
@@ -1,5 +1,5 @@
 [targeting.html]
-  prefs: [dom.webcomponents.enabled:true, security.csp.enable_violation_events:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true, security.csp.enable_violation_events:true]
   expected: TIMEOUT
   [These tests should not fail.]
     expected: NOTRUN
diff --git a/testing/web-platform/meta/css/css-backgrounds/background-size-027.html.ini b/testing/web-platform/meta/css/css-backgrounds/background-size-027.html.ini
index cafa62623047..91a6e2c2efc4 100644
--- a/testing/web-platform/meta/css/css-backgrounds/background-size-027.html.ini
+++ b/testing/web-platform/meta/css/css-backgrounds/background-size-027.html.ini
@@ -1,2 +1,2 @@
 [background-size-027.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/css/css-scoping-1/__dir__.ini b/testing/web-platform/meta/css/css-scoping-1/__dir__.ini
index fdbcfd6058dd..fbdeb90f12e8 100644
--- a/testing/web-platform/meta/css/css-scoping-1/__dir__.ini
+++ b/testing/web-platform/meta/css/css-scoping-1/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.webcomponents.enabled:true]
+prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/css/css-scoping/__dir__.ini b/testing/web-platform/meta/css/css-scoping/__dir__.ini
index a942ccf7b5f5..dddd540bee62 100644
--- a/testing/web-platform/meta/css/css-scoping/__dir__.ini
+++ b/testing/web-platform/meta/css/css-scoping/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: [dom.webcomponents.enabled:true]
+prefs: [dom.webcomponents.shadowdom.enabled:true]
 
diff --git a/testing/web-platform/meta/css/cssom-view/elementsFromPoint-shadowroot.html.ini b/testing/web-platform/meta/css/cssom-view/elementsFromPoint-shadowroot.html.ini
index 79588bb3612f..7357502399af 100644
--- a/testing/web-platform/meta/css/cssom-view/elementsFromPoint-shadowroot.html.ini
+++ b/testing/web-platform/meta/css/cssom-view/elementsFromPoint-shadowroot.html.ini
@@ -1,5 +1,5 @@
 [elementsFromPoint-shadowroot.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
   [elementsFromPoint on the document root should not return elements in shadow trees]
     expected: FAIL
 
diff --git a/testing/web-platform/meta/css/cssom-view/scrollIntoView-shadow.html.ini b/testing/web-platform/meta/css/cssom-view/scrollIntoView-shadow.html.ini
index 306685d1122f..48d3ab883700 100644
--- a/testing/web-platform/meta/css/cssom-view/scrollIntoView-shadow.html.ini
+++ b/testing/web-platform/meta/css/cssom-view/scrollIntoView-shadow.html.ini
@@ -1,2 +1,2 @@
 [scrollIntoView-shadow.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/css/selectors/__dir__.ini b/testing/web-platform/meta/css/selectors/__dir__.ini
index a942ccf7b5f5..dddd540bee62 100644
--- a/testing/web-platform/meta/css/selectors/__dir__.ini
+++ b/testing/web-platform/meta/css/selectors/__dir__.ini
@@ -1,2 +1,2 @@
-prefs: [dom.webcomponents.enabled:true]
+prefs: [dom.webcomponents.shadowdom.enabled:true]
 
diff --git a/testing/web-platform/meta/css/selectors4/__dir__.ini b/testing/web-platform/meta/css/selectors4/__dir__.ini
index fdbcfd6058dd..fbdeb90f12e8 100644
--- a/testing/web-platform/meta/css/selectors4/__dir__.ini
+++ b/testing/web-platform/meta/css/selectors4/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.webcomponents.enabled:true]
+prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/custom-elements/adopted-callback.html.ini b/testing/web-platform/meta/custom-elements/adopted-callback.html.ini
index 205d42cda823..f32ad09f8f1f 100644
--- a/testing/web-platform/meta/custom-elements/adopted-callback.html.ini
+++ b/testing/web-platform/meta/custom-elements/adopted-callback.html.ini
@@ -1,2 +1,2 @@
 [adopted-callback.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/custom-elements/connected-callbacks.html.ini b/testing/web-platform/meta/custom-elements/connected-callbacks.html.ini
index b0177d78e089..29e9a21a0379 100644
--- a/testing/web-platform/meta/custom-elements/connected-callbacks.html.ini
+++ b/testing/web-platform/meta/custom-elements/connected-callbacks.html.ini
@@ -1,2 +1,2 @@
 [connected-callbacks.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/custom-elements/disconnected-callbacks.html.ini b/testing/web-platform/meta/custom-elements/disconnected-callbacks.html.ini
index db8d69252576..9796f28d5f44 100644
--- a/testing/web-platform/meta/custom-elements/disconnected-callbacks.html.ini
+++ b/testing/web-platform/meta/custom-elements/disconnected-callbacks.html.ini
@@ -1,2 +1,2 @@
 [disconnected-callbacks.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/custom-elements/reactions/Element.html.ini b/testing/web-platform/meta/custom-elements/reactions/Element.html.ini
index 755f35c1fdc2..710523b964e3 100644
--- a/testing/web-platform/meta/custom-elements/reactions/Element.html.ini
+++ b/testing/web-platform/meta/custom-elements/reactions/Element.html.ini
@@ -1,5 +1,5 @@
 [Element.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
   [removeAttribute on Element must not enqueue an attributeChanged reaction when removing an attribute that does not exist]
     expected: FAIL
 
diff --git a/testing/web-platform/meta/custom-elements/reactions/ShadowRoot.html.ini b/testing/web-platform/meta/custom-elements/reactions/ShadowRoot.html.ini
index c197795a3dd9..c5011b3ebeb6 100644
--- a/testing/web-platform/meta/custom-elements/reactions/ShadowRoot.html.ini
+++ b/testing/web-platform/meta/custom-elements/reactions/ShadowRoot.html.ini
@@ -1,2 +1,2 @@
 [ShadowRoot.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/dom/interfaces.html.ini b/testing/web-platform/meta/dom/interfaces.html.ini
index 9d6e83b3a902..ec680563f181 100644
--- a/testing/web-platform/meta/dom/interfaces.html.ini
+++ b/testing/web-platform/meta/dom/interfaces.html.ini
@@ -1,5 +1,5 @@
 [interfaces.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
   [Document interface: attribute origin]
     expected: FAIL
     bug: 931884
diff --git a/testing/web-platform/meta/html/dom/interfaces.html.ini b/testing/web-platform/meta/html/dom/interfaces.html.ini
index d356f75dc4fc..29642a2d0f83 100644
--- a/testing/web-platform/meta/html/dom/interfaces.html.ini
+++ b/testing/web-platform/meta/html/dom/interfaces.html.ini
@@ -1,5 +1,5 @@
 [interfaces.html]
-  prefs: [dom.forms.inputmode:true, dom.dialog_element.enabled:true, dom.forms.autocomplete.formautofill:true, dom.webcomponents.enabled:true, dom.moduleScripts.enabled:true]
+  prefs: [dom.forms.inputmode:true, dom.dialog_element.enabled:true, dom.forms.autocomplete.formautofill:true, dom.webcomponents.shadowdom.enabled:true, dom.moduleScripts.enabled:true]
 
   [Document interface: attribute domain]
     expected: FAIL
diff --git a/testing/web-platform/meta/html/dom/reflection-misc.html.ini b/testing/web-platform/meta/html/dom/reflection-misc.html.ini
index 8794b4359dfe..ca6cf580a4c6 100644
--- a/testing/web-platform/meta/html/dom/reflection-misc.html.ini
+++ b/testing/web-platform/meta/html/dom/reflection-misc.html.ini
@@ -1,5 +1,5 @@
 [reflection-misc.html]
-  prefs: [dom.dialog_element.enabled: true, dom.webcomponents.enabled:true, dom.moduleScripts.enabled:true]
+  prefs: [dom.dialog_element.enabled: true, dom.webcomponents.shadowdom.enabled:true, dom.moduleScripts.enabled:true]
 
   [html.tabIndex: setAttribute() to object "3" followed by getAttribute()]
     expected: FAIL
diff --git a/testing/web-platform/meta/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/not-in-shadow-tree.html.ini b/testing/web-platform/meta/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/not-in-shadow-tree.html.ini
index cd8a1624bacc..f1d283086524 100644
--- a/testing/web-platform/meta/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/not-in-shadow-tree.html.ini
+++ b/testing/web-platform/meta/html/semantics/document-metadata/the-meta-element/pragma-directives/attr-meta-http-equiv-refresh/not-in-shadow-tree.html.ini
@@ -1,2 +1,2 @@
 [not-in-shadow-tree.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/html/semantics/forms/the-form-element/form-elements-filter.html.ini b/testing/web-platform/meta/html/semantics/forms/the-form-element/form-elements-filter.html.ini
index b5430eee7805..6939a69571f4 100644
--- a/testing/web-platform/meta/html/semantics/forms/the-form-element/form-elements-filter.html.ini
+++ b/testing/web-platform/meta/html/semantics/forms/the-form-element/form-elements-filter.html.ini
@@ -1,2 +1,2 @@
 [form-elements-filter.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini b/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini
index f783e767a251..11eee36d213c 100644
--- a/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini
+++ b/testing/web-platform/meta/html/semantics/forms/the-label-element/label-attributes.html.ini
@@ -1,2 +1,2 @@
 [label-attributes.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/html/semantics/interfaces.html.ini b/testing/web-platform/meta/html/semantics/interfaces.html.ini
index 392628602103..ffd0461e84d0 100644
--- a/testing/web-platform/meta/html/semantics/interfaces.html.ini
+++ b/testing/web-platform/meta/html/semantics/interfaces.html.ini
@@ -1,5 +1,5 @@
 [interfaces.html]
-  prefs: [dom.dialog_element.enabled: true, dom.webcomponents.enabled:true]
+  prefs: [dom.dialog_element.enabled: true, dom.webcomponents.shadowdom.enabled:true]
   [Interfaces for image]
     expected: FAIL
 
diff --git a/testing/web-platform/meta/intersection-observer/shadow-content.html.ini b/testing/web-platform/meta/intersection-observer/shadow-content.html.ini
index 05863e1139a1..4932fc1539f2 100644
--- a/testing/web-platform/meta/intersection-observer/shadow-content.html.ini
+++ b/testing/web-platform/meta/intersection-observer/shadow-content.html.ini
@@ -1,2 +1,2 @@
 [shadow-content.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/payment-request/interfaces.https.html.ini b/testing/web-platform/meta/payment-request/interfaces.https.html.ini
index a678588892ef..15eb302e5092 100644
--- a/testing/web-platform/meta/payment-request/interfaces.https.html.ini
+++ b/testing/web-platform/meta/payment-request/interfaces.https.html.ini
@@ -1,5 +1,5 @@
 [interfaces.https.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
   [PaymentRequest interface: existence and properties of interface object]
     expected: FAIL
 
diff --git a/testing/web-platform/meta/shadow-dom/__dir__.ini b/testing/web-platform/meta/shadow-dom/__dir__.ini
index fdbcfd6058dd..fbdeb90f12e8 100644
--- a/testing/web-platform/meta/shadow-dom/__dir__.ini
+++ b/testing/web-platform/meta/shadow-dom/__dir__.ini
@@ -1 +1 @@
-prefs: [dom.webcomponents.enabled:true]
+prefs: [dom.webcomponents.shadowdom.enabled:true]
diff --git a/testing/web-platform/meta/touch-events/touch-retargeting.html.ini b/testing/web-platform/meta/touch-events/touch-retargeting.html.ini
index 648052b5a24e..163d3c93fdd8 100644
--- a/testing/web-platform/meta/touch-events/touch-retargeting.html.ini
+++ b/testing/web-platform/meta/touch-events/touch-retargeting.html.ini
@@ -1,5 +1,5 @@
 [touch-retargeting.html]
-  prefs: [dom.webcomponents.enabled:true]
+  prefs: [dom.webcomponents.shadowdom.enabled:true]
   [TouchEvent's touches, targetTouches, and changedTouches should be retargeted.]
     expected: FAIL