Generate a library ID instead of a library name, so that the ID can be used

tools/dom/templates/html/dartium/cpp_implementation.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.
 
 #include "config.h"
 #include "DartWebkitClassIds.h"
 #include "Dart$(INTERFACE).h"
 
@@ skipping 10 matching lines @@
 
 Dart_NativeFunction Dart$(INTERFACE)::resolver(Dart_Handle nameHandle, int argumentCount)
 {
     String name = DartUtilities::toString(nameHandle);
 
 $RESOLVER
     return 0;
 }
 
 const char* const Dart$(INTERFACE)::dartImplementationClassName = "$DART_IMPLEMENTATION_CLASS";
-const char* const Dart$(INTERFACE)::dartImplementationLibraryName = "$DART_IMPLEMENTATION_LIBRARY";
+const int Dart$(INTERFACE)::dartImplementationLibraryId = $(DART_IMPLEMENTATION_LIBRARY_ID);
 const int Dart$(INTERFACE)::dartClassId = $(INTERFACE)ClassId;
 }