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

third_party/WebKit/Source/core/dom/ModuleScript.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 ModuleScript_h
 #define ModuleScript_h
 
 #include "bindings/core/v8/ScriptModule.h"
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/ScriptWrappable.h"
@@ skipping 38 matching lines @@
     return instantiation_state_;
   }
 
   // Implements Step 7.1 of:
   // https://html.spec.whatwg.org/multipage/webappapis.html#internal-module-script-graph-fetching-procedure
   void SetInstantiationErrorAndClearRecord(ScriptValue error);
   // Implements Step 7.2 of:
   // https://html.spec.whatwg.org/multipage/webappapis.html#internal-module-script-graph-fetching-procedure
   void SetInstantiationSuccess();
 
+  v8::Local<v8::Value> CreateInstantiationError(v8::Isolate* isolate) const {

[hiroshige, 2017/04/27 22:56:40]

ModulatorImpl::GetInstantiationError() and
ModuleScript::CreateInstantiationError() looks quite similar in its
interface and developers might be not sure which function to use.

I expect GetInstantiationError() should be preferred because it enforces
the correct |isolate| to be used, if we use the correct modulator.
So how about renaming CreateInstantiationError() to something like
CreateInstantiationErrorInternal() and adding a comment that this should
be used only from ModulatorImpl::GetInstantiationError()?

[kouhei (in TOK), 2017/04/28 00:55:09]

Yes. That's the idea. Done.

[hiroshige, 2017/04/28 01:28:35]

nit: Probably unifying the Create...() and Get...() prefixes might be better.

+    return instantiation_error_.NewLocal(isolate);
+  }
+
   ParserDisposition ParserState() const { return parser_state_; }
   WebURLRequest::FetchCredentialsMode CredentialsMode() const {
     return credentials_mode_;
   }
   const String& Nonce() const { return nonce_; }
 
   DECLARE_TRACE();
   DECLARE_TRACE_WRAPPERS();
 
  private:
@@ skipping 47 matching lines @@
   // https://html.spec.whatwg.org/multipage/webappapis.html#concept-module-script-parser
   const ParserDisposition parser_state_;
 
   // https://html.spec.whatwg.org/multipage/webappapis.html#concept-module-script-credentials-mode
   const WebURLRequest::FetchCredentialsMode credentials_mode_;
 };
 
 }  // namespace blink
 
 #endif