Add NativeValueTraits for ScriptValue to V8Bindings.

Source/bindings/core/v8/V8Binding.h

Index: Source/bindings/core/v8/V8Binding.h
diff --git a/Source/bindings/core/v8/V8Binding.h b/Source/bindings/core/v8/V8Binding.h
index a17bb95f781cb271fc6be12bf9d5d08b6768b52e..6a05dbfffe326fffb368e351f350d895d1defbef 100644
--- a/Source/bindings/core/v8/V8Binding.h
+++ b/Source/bindings/core/v8/V8Binding.h
@@ -609,6 +609,14 @@ struct NativeValueTraits<v8::Handle<v8::Value> > {
     }
 };
 
+template<>
+struct NativeValueTraits<ScriptValue> {
+    static inline ScriptValue nativeValue(const v8::Handle<v8::Value>& value, v8::Isolate* isolate)
+    {
+        return ScriptValue(ScriptState::current(isolate), value);

[haraken, 2014/08/06 00:55:10]

I'm a bit concerned about this. In order to call ScriptState::current(), it must
be guaranteed that the caller site is in a correct ScriptState. I'm not sure if
it's guaranteed for nativeValue() (today and in the future).

Where do you need the nativeValue for ScriptValue, specifically?

+    }
+};
+
 v8::Handle<v8::Value> toV8Sequence(v8::Handle<v8::Value>, uint32_t& length, v8::Isolate*);
 
 // Converts a JavaScript value to an array as per the Web IDL specification: