Give generatored bindings classes a field remembering an index into a cache of handles on the corre…

tools/dom/templates/html/dartium/cpp_header.template

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // WARNING: Do not edit - generated code.
 
 #ifndef Dart$(INTERFACE)_h
 #define Dart$(INTERFACE)_h
 
 #include "bindings/dart/DartDOMWrapper.h"
 $WEBCORE_INCLUDES
 #include <dart_api.h>
 
 namespace WebCore {
 
 struct Dart$INTERFACE {
     static const char* const dartImplementationClassName;
     static const char* const dartImplementationLibraryName;
+    static const int dartClassId;
     typedef $WEBCORE_CLASS_NAME NativeType;
     static const bool isNode = $IS_NODE;
     static const bool isActive = $IS_ACTIVE;
     static const bool isEventTarget = $IS_EVENT_TARGET;
 
 $TO_NATIVE
 $TO_DART
     static Dart_Handle toDart(PassRefPtr< $WEBCORE_CLASS_NAME > value)
     {
         return toDart(value.get());
     }
 
     static Dart_NativeFunction resolver(Dart_Handle name, int argumentCount);
 };
 
 Dart_Handle $(WEBCORE_CLASS_NAME_ESCAPED)_toDart(PassRefPtr< $WEBCORE_CLASS_NAME > value);
 
 namespace Dart$(INTERFACE)Internal {
 $DECLARATIONS
 }
 
 }
 
 #endif // Dart$(INTERFACE)_h