Fix warnings on Win64.

src/handles.cc

 // Copyright 2009 the V8 project authors. 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
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 32 matching lines @@
 namespace internal {
 
 
 v8::ImplementationUtilities::HandleScopeData HandleScope::current_ =
     { -1, NULL, NULL };
 
 
 int HandleScope::NumberOfHandles() {
   int n = HandleScopeImplementer::instance()->blocks()->length();
   if (n == 0) return 0;
-  return ((n - 1) * kHandleBlockSize) +
-      (current_.next - HandleScopeImplementer::instance()->blocks()->last());
+  return ((n - 1) * kHandleBlockSize) + static_cast<int>(
+      (current_.next - HandleScopeImplementer::instance()->blocks()->last()));
 }
 
 
 Object** HandleScope::Extend() {
   Object** result = current_.next;
 
   ASSERT(result == current_.limit);
   // Make sure there's at least one scope on the stack and that the
   // top of the scope stack isn't a barrier.
   if (current_.extensions < 0) {
@@ skipping 713 matching lines @@
   Handle<Map> new_map = Factory::CopyMapDropTransitions(old_map);
   obj->set_map(*new_map);
   new_map->set_needs_loading(true);
   // Store the lazy loading info in the constructor field.  We'll
   // reestablish the constructor from the fixed array after loading.
   new_map->set_constructor(*arr);
   ASSERT(!obj->IsLoaded());
 }
 
 } }  // namespace v8::internal