[WIP] bindings: Introduce PropertyBag

Source/bindings/templates/dictionary_v8.cpp

Index: Source/bindings/templates/dictionary_v8.cpp
diff --git a/Source/bindings/templates/dictionary_v8.cpp b/Source/bindings/templates/dictionary_v8.cpp
index 2b3c32e728c403ff49c79d3063e910323e1fe822..8931159d0c0d8f4eb365b1e9b95e3c7ea9e1dca8 100644
--- a/Source/bindings/templates/dictionary_v8.cpp
+++ b/Source/bindings/templates/dictionary_v8.cpp
@@ -13,15 +13,16 @@
 
 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;