1 files changed, 7 insertions, 0 deletions
diff --git a/dom/base/CustomElementRegistry.h b/dom/base/CustomElementRegistry.h
index 9034dd7ea..8ef0785af 100644
--- a/dom/base/CustomElementRegistry.h
+++ b/dom/base/CustomElementRegistry.h
@@ -128,6 +128,10 @@ struct CustomElementDefinition
 
   // The document custom element order.
   uint32_t mDocOrder;
+
+  bool IsCustomBuiltIn() {
+    return mType != mLocalName;
+  }
 };
 
 class CustomElementRegistry final : public nsISupports,
@@ -155,6 +159,9 @@ public:
   CustomElementDefinition* LookupCustomElementDefinition(
     const nsAString& aLocalName, const nsAString* aIs = nullptr) const;
 
+  CustomElementDefinition* LookupCustomElementDefinition(
+    JSContext* aCx, JSObject *aConstructor) const;
+
   /**
    * Enqueue created callback or register upgrade candidate for
    * newly created custom elements, possibly extending an existing type.