bindings: Use V8 MaybeLocal<> APIs in Dictionary class

Source/bindings/core/v8/Dictionary.h

 /*
  * Copyright (C) 2010 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 26 matching lines @@
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicString.h"
 #include "wtf/text/WTFString.h"
 #include <v8.h>
 
 namespace blink {
 
 // Dictionary class provides ways to retrieve property values as C++ objects
 // from a V8 object. Instances of this class must not outlive V8's handle scope
 // because they hold a V8 value without putting it on persistent handles.
-class Dictionary {
+class Dictionary final {
     ALLOW_ONLY_INLINE_ALLOCATION();
 public:
     Dictionary();
     Dictionary(const v8::Handle<v8::Value>& options, v8::Isolate*, ExceptionState&);
     ~Dictionary();
 
     Dictionary& operator=(const Dictionary&);
 
     // This is different from the default constructor:
     //   * isObject() is true when using createEmpty().
@@ skipping 55 matching lines @@
     };
 
     bool convert(ConversionContext&, const String&, Dictionary&) const;
 
     bool getOwnPropertiesAsStringHashMap(HashMap<String, String>&) const;
     bool getPropertyNames(Vector<String>&) const;
 
     bool hasProperty(const String&) const;
 
     v8::Isolate* isolate() const { return m_isolate; }
+    // Used by DictionaryHelper. This context could be an empty handle and
+    // should be used only for V8 APIs which return MaybeLocal<T>.
+    v8::Local<v8::Context> context() const;
 
     bool getKey(const String& key, v8::Local<v8::Value>&) const;
 
 private:
     v8::Handle<v8::Value> m_options;
     v8::Isolate* m_isolate;
     ExceptionState* m_exceptionState;
 };
 
 template<>
@@ skipping 27 matching lines @@
     static bool convert(const Dictionary&, Dictionary::ConversionContext&, const String& key, T& value);
     template <typename T>
     static bool convert(const Dictionary&, Dictionary::ConversionContext&, const String& key, Nullable<T>& value);
     template <template <typename> class PointerType, typename T>
     static bool convert(const Dictionary&, Dictionary::ConversionContext&, const String& key, PointerType<T>& value);
 };
 
 }
 
 #endif // Dictionary_h