Support new style JS interop

Source/bindings/core/dart/DartJsInteropData.h

Index: Source/bindings/core/dart/DartJsInteropData.h
diff --git a/Source/bindings/core/dart/DartJsInteropData.h b/Source/bindings/core/dart/DartJsInteropData.h
index 653f4d3ba3b5dc4cceb88c2872694b90c25261ac..9eb72ba253b597c00d815884a6275ff6d4d411af 100644
--- a/Source/bindings/core/dart/DartJsInteropData.h
+++ b/Source/bindings/core/dart/DartJsInteropData.h
@@ -39,10 +39,15 @@ namespace blink {
 
 class DartJsInteropData {
 public:
+    DartJsInteropData() { m_jsObjectImplDefined = false; }
+
     v8::Local<v8::Function> captureThisFunction();
     v8::Local<v8::Function> wrapDartFunction();
     v8::Local<v8::Function> instanceofFunction();
 
+    bool jsObjectImplDefined() { return m_jsObjectImplDefined; }
+    void setJsObjectImplDefined() { m_jsObjectImplDefined = true; }
+
 private:
     static v8::Local<v8::Function> cacheFunction(v8::Persistent<v8::Function>* cache, const char* scriptSrc);
 
@@ -50,6 +55,8 @@ private:
     v8::Persistent<v8::Function> m_wrapDartFunction;
     v8::Persistent<v8::Function> m_instanceofFunction;
 
+    bool m_jsObjectImplDefined;
+
     // FIXME: add maps of Dart to V8 and V8 to Dart objects.
 };