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

third_party/WebKit/Source/bindings/templates/dictionary_v8.h.tmpl

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 #ifndef {{v8_original_class}}_h
 #define {{v8_original_class}}_h
 
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
@@ skipping 12 matching lines @@
 inline void v8SetReturnValue(const CallbackInfo& callbackInfo, {{cpp_class}}& impl) {
   v8SetReturnValue(callbackInfo, ToV8(impl, callbackInfo.Holder(), callbackInfo.GetIsolate()));
 }
 
 template <class CallbackInfo>
 inline void v8SetReturnValue(const CallbackInfo& callbackInfo, {{cpp_class}}& impl, v8::Local<v8::Object> creationContext) {
   v8SetReturnValue(callbackInfo, ToV8(impl, creationContext, callbackInfo.GetIsolate()));
 }
 
 template <>
-struct NativeValueTraits<{{cpp_class}}> {
-  static {{cpp_class}} nativeValue(v8::Isolate*, v8::Local<v8::Value>, ExceptionState&);
+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_original_class}}_h
 
 {% endfilter %}{# format_blink_cpp_source_code #}