2 files changed, 8 insertions, 2 deletions
diff --git a/dom/base/CustomElementRegistry.cpp b/dom/base/CustomElementRegistry.cpp
index 0f03b16bd..f17c2c7d9 100644
--- a/dom/base/CustomElementRegistry.cpp
+++ b/dom/base/CustomElementRegistry.cpp
@@ -1044,8 +1044,12 @@ CustomElementReactionsStack::PopAndInvokeElementQueue()
     // element, see https://github.com/w3c/webcomponents/issues/635.
     // We usually report the error to entry global in gecko, so just follow the
     // same behavior here.
+    // This may be null if it's called from parser, see the case of
+    // attributeChangedCallback in
+    // https://html.spec.whatwg.org/multipage/parsing.html#create-an-element-for-the-token
+    // In that case, the exception of callback reactions will be automatically
+    // reported in CallSetup.
     nsIGlobalObject* global = GetEntryGlobal();
-    MOZ_ASSERT(global, "Should always have a entry global here!");
     InvokeReactions(elementQueue, global);
   }
 
diff --git a/dom/base/nsContentCreatorFunctions.h b/dom/base/nsContentCreatorFunctions.h
index 9576d9ba8..a5c210500 100644
--- a/dom/base/nsContentCreatorFunctions.h
+++ b/dom/base/nsContentCreatorFunctions.h
@@ -24,6 +24,7 @@ namespace mozilla {
 namespace dom {
 class Element;
 class NodeInfo;
+struct CustomElementDefinition;
 } // namespace dom
 } // namespace mozilla
 
@@ -41,7 +42,8 @@ nsresult
 NS_NewHTMLElement(mozilla::dom::Element** aResult,
                   already_AddRefed<mozilla::dom::NodeInfo>&& aNodeInfo,
                   mozilla::dom::FromParser aFromParser,
-                  const nsAString* aIs = nullptr);
+                  const nsAString* aIs = nullptr,
+                  mozilla::dom::CustomElementDefinition* aDefinition = nullptr);
 
 // First argument should be nsHTMLTag, but that adds dependency to parser
 // for a bunch of files.