Bug 1414490 - Permanently undefine the insertion point at EOF. r=smaug.

MozReview-Commit-ID: Kijs3Rxhq0X

dom/html/nsHTMLDocument.cpp

@@ -1974,8 +1974,11 @@ nsHTMLDocument::WriteCommon(JSContext *cx,
                                       mDocumentURI);
       return NS_OK;
     }
+    // The spec doesn't tell us to ignore opens from here, but we need to
+    // ensure opens are ignored here.
+    IgnoreOpensDuringUnload ignoreOpenGuard(this);
     mParser->Terminate();
-    NS_ASSERTION(!mParser, "mParser should have been null'd out");
+    MOZ_RELEASE_ASSERT(!mParser, "mParser should have been null'd out");
   }
 
   if (!mParser) {