WIP bindings: Add support for the record<K,V> WebIDL type.

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 13 matching lines @@
   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&);
+  using ImplType = {{cpp_class}};

[Yuki, 2017/03/02 07:47:28]

nit: Can we have this declaration as the default definition of ImplType in
NativeValueTraits.h ?

[Raphael Kubo da Costa (rakuco), 2017/03/02 08:16:24]

I tried doing that earlier, but any template specialization hides the definition
so it didn't work and I had to add those back.

[Yuki, 2017/03/02 13:00:25]

I guess that the following would work.

  template <typename T>
  struct NativeValueTraitsBase {
    using ImplType = T;
  };

  template <typename T>
  struct NativeValueTraits : public NativeValueTraitsBase<T> {
     // ...
  };

  template <>
  struct NativeValueTraits<ActualType> : public
NativeValueTraitsBase<ActualType> {
    // ...
  };

Having said that, it's not shorter than the current CL, although we can easily
add more things in NativeValueTraitsBase.  I'm fine with either way.

+  {{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 #}