Use Dart_InstanceIsSubtypeOf to check if instance is a direct subtype of specified type.

Source/bindings/dart/DartDOMWrapper.h

Index: Source/bindings/dart/DartDOMWrapper.h
===================================================================
--- Source/bindings/dart/DartDOMWrapper.h	(revision 1430)
+++ Source/bindings/dart/DartDOMWrapper.h	(working copy)
@@ -142,8 +142,7 @@
         if (Dart_IsNull(wrapper))
             return 0;
 
-        // FIXME: support cross-domain wrappers.
-        if (!instanceOf<BindingsClass>(domData, wrapper)) {
+        if (!subtypeOf<BindingsClass>(domData, wrapper)) {
             String message = String("Invalid class: expected instance of ") + BindingsClass::dartImplementationClassName;
             exception = DartUtilities::stringToDartString(message);
             return 0;
@@ -163,13 +162,14 @@
     }
 
     template <class BindingsClass>
-    static bool instanceOf(DartDOMData* domData, Dart_Handle wrapper)
+    static bool subtypeOf(DartDOMData* domData, Dart_Handle wrapper)
     {
         Dart_PersistentHandle type = dartClass<BindingsClass>(domData);
 
-        bool isInstanceOf = false;
-        Dart_Handle result = Dart_ObjectIsType(wrapper, type, &isInstanceOf);

[vsm, 2013/10/14 15:44:09]

Siva: Just curious, what's the semantic difference between ObjectIsType and
InstanceIsSubtypeOf?  Why is the latter more efficient?

[siva, 2013/10/14 15:55:06]

Dart_InstanceIsSubtypeOf just does a straight sub class check without looking
into interfaces etc. It also only deals with non parameterized types which is
what all these Web native types are.
(This will also take care of the issue 11008).

On 2013/10/14 15:44:09, vsm wrote:

-        return isInstanceOf;
+        bool isSubtypeOf = false;
+        Dart_Handle result = Dart_InstanceIsSubtypeOf(wrapper, type, &isSubtypeOf);
+        ASSERT(!Dart_IsError(result));
+        return isSubtypeOf;
     }
 
     template <class WebKitClass>