diff --git a/testing/web-platform/meta/MANIFEST.json b/testing/web-platform/meta/MANIFEST.json
index b67ef8735182..b1fa91ce452e 100644
--- a/testing/web-platform/meta/MANIFEST.json
+++ b/testing/web-platform/meta/MANIFEST.json
@@ -286735,6 +286735,16 @@
      {}
     ]
    ],
+   "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-async-frame.html": [
+    [
+     {}
+    ]
+   ],
+   "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-frame.html": [
+    [
+     {}
+    ]
+   ],
    "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/encoding-frame.html": [
     [
      {}
@@ -351749,6 +351759,12 @@
      {}
     ]
    ],
+   "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/aborted-parser.window.js": [
+    [
+     "/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/aborted-parser.window.html",
+     {}
+    ]
+   ],
    "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/document.open-01.xhtml": [
     [
      "/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/document.open-01.xhtml",
@@ -590156,6 +590172,10 @@
    "ea3ff6e58680da8c3f08e7f26ebc738d82703801",
    "testharness"
   ],
+  "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/aborted-parser.window.js": [
+   "0ef6dab1d5e2364a0a75513469e339c20b14c674",
+   "testharness"
+  ],
   "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/document.open-01.xhtml": [
    "cb059c7c17320c0e63e9453d3a0486a8a94b060a",
    "testharness"
@@ -590192,6 +590212,14 @@
    "b4cdd98c6eb9a3946b49a6876c62c7e35501f413",
    "testharness"
   ],
+  "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-async-frame.html": [
+   "38be68cf85bbe4cef461963768fe1390733d67db",
+   "support"
+  ],
+  "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-frame.html": [
+   "4cb26a783d232652a580e511e439b8bfaac04dfe",
+   "support"
+  ],
   "html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/encoding-frame.html": [
    "1d8ae9f75fe05343c1858caad637c9f7602c9f28",
    "support"
diff --git a/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/aborted-parser.window.js b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/aborted-parser.window.js
new file mode 100644
index 000000000000..1d94de8a7c9f
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/aborted-parser.window.js
@@ -0,0 +1,28 @@
+// document.open() bails out early if there is an **active parser** with
+// non-zero script nesting level. window.stop() aborts the current parser and
+// makes it no longer active, and should allow document.open() to work.
+// For more details, see https://bugzilla.mozilla.org/show_bug.cgi?id=1475000.
+
+window.handlers = {};
+
+async_test(t => {
+  const frame = document.body.appendChild(document.createElement("iframe"));
+  frame.src = "resources/aborted-parser-frame.html";
+  window.handlers.afterOpen = t.step_func_done(() => {
+    const openCalled = frame.contentDocument.childNodes.length === 0;
+    frame.remove();
+    assert_true(openCalled, "child document should be empty");
+  });
+}, "document.open() after parser is aborted");
+
+// Note: This test should pass even if window.close() is not there, as
+// document.open() is not executed synchronously in an inline script.
+async_test(t => {
+  const frame = document.body.appendChild(document.createElement("iframe"));
+  frame.src = "resources/aborted-parser-async-frame.html";
+  window.handlers.afterOpenAsync = t.step_func_done(() => {
+    const openCalled = frame.contentDocument.childNodes.length === 0;
+    frame.remove();
+    assert_true(openCalled, "child document should be empty");
+  });
+}, "async document.open() after parser is aborted");
diff --git a/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-async-frame.html b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-async-frame.html
new file mode 100644
index 000000000000..d5535630be05
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-async-frame.html
@@ -0,0 +1,9 @@
+<!doctype html>
+<p>Text</p>
+<script>
+window.stop();
+parent.step_timeout(() => {
+  document.open();
+  parent.handlers.afterOpenAsync();
+}, 10);
+</script>
diff --git a/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-frame.html b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-frame.html
new file mode 100644
index 000000000000..d9ec23590bf9
--- /dev/null
+++ b/testing/web-platform/tests/html/webappapis/dynamic-markup-insertion/opening-the-input-stream/resources/aborted-parser-frame.html
@@ -0,0 +1,7 @@
+<!doctype html>
+<p>Text</p>
+<script>
+window.stop();
+document.open();
+parent.handlers.afterOpen();
+</script>