diff --git a/testing/web-platform/tests/editing/crashtests/insertAdjacentElement-with-DOMSubtreeModified.html b/testing/web-platform/tests/editing/crashtests/insertAdjacentElement-with-DOMSubtreeModified.html
new file mode 100644
index 000000000000..781f99007b79
--- /dev/null
+++ b/testing/web-platform/tests/editing/crashtests/insertAdjacentElement-with-DOMSubtreeModified.html
@@ -0,0 +1,215 @@
+<
+!
+DOCTYPE
+html
+>
+<
+head
+>
+<
+script
+src
+=
+"
+.
+.
+/
+resources
+/
+js
+-
+test
+.
+js
+"
+>
+<
+/
+script
+>
+<
+script
+>
+function
+onLoad
+(
+)
+{
+const
+x1
+=
+document
+.
+getElementById
+(
+'
+x1
+'
+)
+;
+x1
+.
+addEventListener
+(
+'
+DOMSubtreeModified
+'
+(
+)
+=
+>
+{
+const
+x2
+=
+document
+.
+getElementById
+(
+'
+x2
+'
+)
+;
+x2
+.
+contentDocument
+;
+}
+)
+;
+x1
+.
+setAttribute
+(
+'
+inputmode
+'
+'
+url
+'
+)
+;
+}
+function
+insertAdjacent
+(
+)
+{
+const
+x2
+=
+document
+.
+getElementById
+(
+'
+x2
+'
+)
+;
+const
+x3
+=
+document
+.
+getElementById
+(
+'
+x3
+'
+)
+;
+document
+.
+onreadystatechange
+=
+insertAdjacent
+;
+x3
+.
+insertAdjacentElement
+(
+'
+beforebegin
+'
+x2
+)
+;
+}
+<
+/
+script
+>
+<
+/
+head
+>
+<
+body
+onload
+=
+"
+onLoad
+(
+)
+"
+>
+<
+div
+id
+=
+"
+x1
+"
+>
+<
+/
+div
+>
+<
+object
+id
+=
+"
+x2
+"
+data
+=
+"
+invalid
+-
+url
+"
+onerror
+=
+"
+insertAdjacent
+(
+)
+"
+>
+<
+/
+object
+>
+<
+div
+id
+=
+"
+x3
+"
+>
+<
+/
+div
+>
+<
+/
+body
+>
+<
+/
+html
+>