[bindings] Introduce ScriptValue.to<T> to convert to native values.

Source/bindings/core/v8/ScriptValue.h

Index: Source/bindings/core/v8/ScriptValue.h
diff --git a/Source/bindings/core/v8/ScriptValue.h b/Source/bindings/core/v8/ScriptValue.h
index ca543728397bfa153f717b246367ab07a5b15eb2..f1b220b1b9c1cd374727789cd720562084b9f7e3 100644
--- a/Source/bindings/core/v8/ScriptValue.h
+++ b/Source/bindings/core/v8/ScriptValue.h
@@ -41,8 +41,12 @@
 
 namespace blink {
 
+class ExceptionState;
 class JSONValue;
 
+template <typename T>
+T script_value_cast(const v8::Local<v8::Value>&, v8::Isolate*, ExceptionState&);
+
 class CORE_EXPORT ScriptValue final {
 public:
     template<typename T>
@@ -51,6 +55,12 @@ public:
         return ScriptValue(scriptState, toV8(value, scriptState->context()->Global(), scriptState->isolate()));
     }
 
+    template<typename T>
+    T to(ExceptionState& exceptionState) const
+    {
+        return script_value_cast<T>(v8Value(), isolate(), exceptionState);

[haraken, 2015/03/14 01:27:19]

I'm wondering why we cannot simply call:

  NativeValueTraits<T>::nativeValue(v8Value(), isolate, exceptionState);

+    }
+
     ScriptValue() { }
 
     ScriptValue(ScriptState* scriptState, v8::Handle<v8::Value> value)