Improve Dart Debugger performance and robustness by creating Dart wrappers using the standard SetNa…

Source/bindings/dart/DartDOMWrapper.h

 // Copyright 2011, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //    * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //    * Redistributions in binary form must reproduce the above
@@ skipping 170 matching lines @@
         DartApiScope scope;
         Dart_Handle result = Dart_SetNativeInstanceField(wrapper, index, reinterpret_cast<intptr_t>(pointer));
         UNUSED_PARAM(result);
         ASSERT(!Dart_IsError(result));
     }
 
     static void* readNativePointer(Dart_Handle wrapper, int index)
     {
         intptr_t value;
         Dart_Handle result = Dart_GetNativeInstanceField(wrapper, index, &value);
-        ASSERT(!Dart_IsError(result));
-        UNUSED_PARAM(result);
+        // FIXME: the fact that we return 0 on error rather than asserting is
+        // somewhat of a hack. We currently make this method return 0 because
+        // we reuse this method to verify that objects are actually native
+        // Node objects rather than objects that implement the Node interface.
+        if (Dart_IsError(result))
+            return 0;
         return reinterpret_cast<void*>(value);
     }
 
     template <class BindingsClass>
     static void wrapperWeakCallback(Dart_WeakPersistentHandle, void* peer)
     {
         typedef DartDOMWrapperTraits<BindingsClass> Traits;
         DartDOMData* domData = DartDOMData::current();
         typename BindingsClass::NativeType* domObject = static_cast<typename BindingsClass::NativeType*>(peer);
         ASSERT(DartDOMWrapperTraits<BindingsClass>::MapTraits::domMap(domData)->contains(domObject));
@@ skipping 78 matching lines @@
         static DartMessagePortMap* domMap(DartDOMData* domData) { return domData->messagePortMap(); }
     };
     typedef MessagePortMapTraits MapTraits;
     typedef DartDOMWrapperActiveTraits<DartMessagePort, false> ActiveTraits;
     typedef DartDOMWrapperEventTargetTraits<DartMessagePort, true> EventTargetTraits;
 };
 
 }
 
 #endif // DartDOMWrapper_h