bindings: Use Maybe APIs in ScriptPromise

Source/bindings/core/v8/ScriptValue.h

 /*
  * Copyright (C) 2008, 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 49 matching lines @@
 
     ScriptValue() { }
 
     ScriptValue(ScriptState* scriptState, v8::Handle<v8::Value> value)
         : m_scriptState(scriptState)
         , m_value(value.IsEmpty() ? nullptr : SharedPersistent<v8::Value>::create(value, scriptState->isolate()))
     {
         ASSERT(isEmpty() || m_scriptState);
     }
 
+    template <typename T>
+    ScriptValue(ScriptState* scriptState, v8::MaybeLocal<T> value)
+        : m_scriptState(scriptState)
+        , m_value(value.IsEmpty() ? nullptr : SharedPersistent<v8::Value>::create(value.ToLocalChecked(), scriptState->isolate()))
+    {
+        ASSERT(isEmpty() || m_scriptState);
+    }
+
     ScriptValue(const ScriptValue& value)
         : m_scriptState(value.m_scriptState)
         , m_value(value.m_value)
     {
         ASSERT(isEmpty() || m_scriptState);
     }
 
     ScriptState* scriptState() const
     {
         return m_scriptState.get();
     }
 
     v8::Isolate* isolate() const
     {
         return m_scriptState ? m_scriptState->isolate() : v8::Isolate::GetCurrent();
     }
 
+    v8::Local<v8::Context> context() const
+    {
+        return m_scriptState ? isolate()->GetCurrentContext() : v8::Local<v8::Context>();

[haraken, 2015/03/25 04:29:59]

This seems wrong. We need to use m_scriptState->context().

Also I don't think it is valid to return an empty context from this method. If
an empty context is returned, the caller side will crash when the empty context
is passed in to a next V8 API.

[bashi, 2015/03/25 04:56:00]

Done.

+    }
+
     ScriptValue& operator=(const ScriptValue& value)
     {
         if (this != &value) {
             m_scriptState = value.m_scriptState;
             m_value = value.m_value;
         }
         return *this;
     }
 
     bool operator==(const ScriptValue& value) const
@@ skipping 61 matching lines @@
     static ScriptValue createNull(ScriptState*);
 
 private:
     RefPtr<ScriptState> m_scriptState;
     RefPtr<SharedPersistent<v8::Value>> m_value;
 };
 
 } // namespace blink
 
 #endif // ScriptValue_h