Try fix win64 build.

src/bootstrapper.cc

 // Copyright 2006-2008 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 1336 matching lines @@
 static Handle<JSObject> ResolveCustomCallGeneratorHolder(
     Handle<Context> global_context,
     const char* holder_expr) {
   Handle<GlobalObject> global(global_context->global());
   const char* period_pos = strchr(holder_expr, '.');
   if (period_pos == NULL) {
     return Handle<JSObject>::cast(
         GetProperty(global, Factory::LookupAsciiSymbol(holder_expr)));
   }
   ASSERT_EQ(".prototype", period_pos);
-  Vector<const char> property(holder_expr, period_pos - holder_expr);
+  Vector<const char> property(holder_expr,
+                              static_cast<int>(period_pos - holder_expr));
   Handle<JSFunction> function = Handle<JSFunction>::cast(
       GetProperty(global, Factory::LookupSymbol(property)));
   return Handle<JSObject>(JSObject::cast(function->prototype()));
 }
 
 
 static void InstallCustomCallGenerator(Handle<JSObject> holder,
                                        const char* function_name,
                                        int id) {
   Handle<String> name = Factory::LookupAsciiSymbol(function_name);
@@ skipping 480 matching lines @@
 }
 
 
 // Restore statics that are thread local.
 char* BootstrapperActive::RestoreState(char* from) {
   nesting_ = *reinterpret_cast<int*>(from);
   return from + sizeof(nesting_);
 }
 
 } }  // namespace v8::internal