[ES6 modules] Return previous error when an instantiation is reattempt.

third_party/WebKit/Source/core/dom/ModulatorImpl.h

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ModulatorImpl_h
 #define ModulatorImpl_h
 
 #include "bindings/core/v8/ScriptModule.h"
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "bindings/core/v8/TraceWrapperMember.h"
@@ skipping 43 matching lines @@
                    ModuleGraphLevel,
                    SingleModuleClient*) override;
   ModuleScript* GetFetchedModuleScript(const KURL&) override;
   void FetchNewSingleModule(const ModuleScriptFetchRequest&,
                             ModuleGraphLevel,
                             ModuleScriptLoaderClient*) override;
   ScriptModule CompileModule(const String& script,
                              const String& url_str,
                              AccessControlStatus) override;
   ScriptValue InstantiateModule(ScriptModule) override;
+  ScriptValue GetInstantiationError(const ModuleScript*) override;
   Vector<String> ModuleRequestsFromScriptModule(ScriptModule) override;
   void ExecuteModule(const ModuleScript*) override;
 
   ModulatorImpl(RefPtr<ScriptState>, RefPtr<WebTaskRunner>, ResourceFetcher*);
 
   ExecutionContext* GetExecutionContext() const;
 
   RefPtr<ScriptState> script_state_;
   RefPtr<WebTaskRunner> task_runner_;
   Member<ResourceFetcher> fetcher_;
   TraceWrapperMember<ModuleMap> map_;
   Member<ModuleScriptLoaderRegistry> loader_registry_;
   Member<ModuleTreeLinkerRegistry> tree_linker_registry_;
   Member<ScriptModuleResolver> script_module_resolver_;
 };
 
 }  // namespace blink
 
 #endif