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

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

Index: third_party/WebKit/Source/bindings/templates/union_container.h.tmpl
diff --git a/third_party/WebKit/Source/bindings/templates/union_container.h.tmpl b/third_party/WebKit/Source/bindings/templates/union_container.h.tmpl
index fd29d46cc6c32b1f25784fafab5da84d7a94faac..29453cfaf6d8dc6e96b17d4844a78ecaa12edeee 100644
--- a/third_party/WebKit/Source/bindings/templates/union_container.h.tmpl
+++ b/third_party/WebKit/Source/bindings/templates/union_container.h.tmpl
@@ -66,10 +66,15 @@ inline void v8SetReturnValue(const CallbackInfo& callbackInfo, {{cpp_class}}& im
 }
 
 template <>
-struct NativeValueTraits<{{cpp_class}}> {
+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
 
 // We need to set canInitializeWithMemset=true because HeapVector supports