[WIP Prototype] ES6 https://html.spec.whatwg.org/#fetch-a-single-module-script implementation

third_party/WebKit/Source/bindings/core/v8/V8DOMWrapper.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 54 matching lines @@
     // TODO(yukishiino): This code does not create a wrapper with
     // the correct settings.  Should follow the same way as
     // V8PerContextData::createWrapperFromCache, though there is no need to
     // cache resulting objects or their constructors.
     const DOMWrapperWorld& world = DOMWrapperWorld::World(scope.GetContext());
     wrapper = type->domTemplate(isolate, world)
                   ->InstanceTemplate()
                   ->NewInstance(scope.GetContext())
                   .ToLocalChecked();
   }
+  DCHECK(!wrapper.IsEmpty());
   return wrapper;
 }
 
 bool V8DOMWrapper::IsWrapper(v8::Isolate* isolate, v8::Local<v8::Value> value) {
   if (value.IsEmpty() || !value->IsObject())
     return false;
   v8::Local<v8::Object> object = v8::Local<v8::Object>::Cast(value);
 
   if (object->InternalFieldCount() < kV8DefaultWrapperInternalFieldCount)
     return false;
@@ skipping 65 matching lines @@
   ExceptionState exception_state(isolate, ExceptionState::kConstructionContext,
                                  "Location");
   LocalDOMWindow* calling_window = CurrentDOMWindow(isolate);
   LocalDOMWindow* target_window = ToLocalDOMWindow(context_);
   exception_state.ThrowSecurityError(
       target_window->SanitizedCrossDomainAccessErrorMessage(calling_window),
       target_window->CrossDomainAccessErrorMessage(calling_window));
 }
 
 }  // namespace blink