Run Mutation Observer and Custom Element callbacks consistently at microtask checkpoint

Source/bindings/scripts/CodeGeneratorV8.pm

Index: Source/bindings/scripts/CodeGeneratorV8.pm
diff --git a/Source/bindings/scripts/CodeGeneratorV8.pm b/Source/bindings/scripts/CodeGeneratorV8.pm
index a21c25921389f856fbf4708f8ec1e16275e5a23e..fe1b3a1b3ff0d9b6a8b43c982fcd16729f6f7fb3 100644
--- a/Source/bindings/scripts/CodeGeneratorV8.pm
+++ b/Source/bindings/scripts/CodeGeneratorV8.pm
@@ -1701,9 +1701,9 @@ sub GenerateCustomElementInvocationScopeIfNeeded
             die "IDL error: [Reflect] and [DeliverCustomElementCallbacks] cannot coexist yet";
         }
 
-        AddToImplIncludes("core/dom/CustomElementRegistry.h");
+        AddToImplIncludes("core/dom/CustomElementCallbackDispatcher.h");
         $code .= <<END;
-    CustomElementRegistry::CallbackDeliveryScope deliveryScope;
+    CustomElementCallbackDispatcher::CallbackDeliveryScope deliveryScope;
 END
     }
     return $code;