Add target for webkit_compositor_unittests

webkit/compositor/test/run_all_unittests.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <base/test/test_suite.h>
 #include <gmock/gmock.h>
 #include <webkit/support/webkit_support.h>
 
 int main(int argc, char** argv) {
   ::testing::InitGoogleMock(&argc, argv);
   TestSuite testSuite(argc, argv);
   webkit_support::SetUpTestEnvironmentForUnitTests();
   int result = testSuite.Run();
   webkit_support::TearDownTestEnvironment();
 
   return result;
 }