[WIP] bindings: Introduce PropertyBag

Source/bindings/templates/dictionary_v8.cpp

 // Copyright 2014 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.
 
 // This file has been auto-generated by {{code_generator}}. DO NOT MODIFY!
 
 #include "config.h"
 #include "{{v8_class}}.h"
 
 {% for filename in cpp_includes if filename != '%s.h' % v8_class %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
 
-{{cpp_class}}* {{v8_class}}::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value)
+{{cpp_class}}* {{v8_class}}::toImpl(v8::Isolate* isolate, v8::Handle<v8::Value> v8Value, ExceptionState& exceptionState)
 {
     {{cpp_class}}* impl = {{cpp_class}}::create();
-    // FIXME: Do not use Dictionary and DictionaryHelper
-    // https://crbug.com/321462
-    Dictionary dictionary(v8Value, isolate);
+    if (v8Value.IsEmpty() || !v8Value->IsObject())
+        return impl;
+    v8::Local<v8::Object> v8Object = v8Value->ToObject();
+    PropertyBag bag(isolate, v8Object, exceptionState);
     {% for member in members %}
     {{member.cpp_type}} {{member.name}};
-    if (DictionaryHelper::get(dictionary, "{{member.name}}", {{member.name}}))
+    if (bag.get("{{member.name}}", {{member.name}}))
         impl->{{member.setter_name}}({{member.name}});
     {% endfor %}
     return impl;
 }
 
 v8::Handle<v8::Value> toV8({{cpp_class}}* impl, v8::Handle<v8::Object> creationContext, v8::Isolate* isolate)
 {
     v8::Handle<v8::Object> v8Object = v8::Object::New(isolate);
     {% for member in members %}
     if (impl->{{member.has_method_name}}())
         v8Object->Set(v8String(isolate, "{{member.name}}"), {{member.cpp_value_to_v8_value}});
     {% if member.v8_default_value %}
     else
         v8Object->Set(v8String(isolate, "{{member.name}}"), {{member.v8_default_value}});
     {% endif %}
     {% endfor %}
     return v8Object;
 }
 
 } // namespace blink