bindings: Add C++ versions of WebIDL types and generalize NativeValueTraits.

third_party/WebKit/Source/bindings/templates/interface.h.tmpl

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 #ifndef {{v8_class}}_h
 #define {{v8_class}}_h
 
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
@@ skipping 255 matching lines @@
  private:
   static InstallTemplateFunction install{{v8_class}}TemplateFunction;
   {% endif %}
 };
 
 {% if has_event_constructor %}
 {{exported}}bool initialize{{cpp_class}}({{cpp_class}}Init&, const Dictionary&, ExceptionState&, const v8::FunctionCallbackInfo<v8::Value>& info);
 
 {% endif %}
 template <>
+struct NativeValueTraits<{{cpp_class}}> : public NativeValueTraitsBase<{{cpp_class}}> {
+  {{exported}}static {{cpp_class}}* nativeValue(v8::Isolate*, v8::Local<v8::Value>, ExceptionState&);
+};
+
+template <>
 struct V8TypeOf<{{cpp_class}}> {
   typedef {{v8_class}} Type;
 };
 
 }  // namespace blink
 
 #endif  // {{v8_class}}_h
 
 {% endfilter %}{# format_blink_cpp_source_code #}