[ChromeDriver] Select the main frame if a non-existant child frame is targeted.

chrome/chrome_tests.gypi

 # Copyright 2013 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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 856 matching lines @@
         'test/chromedriver/dom_tracker_unittest.cc',
         'test/chromedriver/fake_session_accessor.cc',
         'test/chromedriver/fake_session_accessor.h',
         'test/chromedriver/frame_tracker_unittest.cc',
         'test/chromedriver/navigation_tracker_unittest.cc',
         'test/chromedriver/server/http_handler_unittest.cc',
         'test/chromedriver/server/http_response_unittest.cc',
         'test/chromedriver/session_command_unittest.cc',
         'test/chromedriver/session_unittest.cc',
         'test/chromedriver/status_unittest.cc',
+        'test/chromedriver/stub_chrome.cc',
+        'test/chromedriver/stub_chrome.h',
         'test/chromedriver/synchronized_map_unittest.cc',
       ],
     },
     # ChromeDriver2 tests that aren't run on the main buildbot. Available
     # as an optional test type on trybots.
     {
       'target_name': 'chromedriver2_tests',
       'type': 'executable',
       'dependencies': [
         'chromedriver2_lib',
@@ skipping 2121 matching lines @@
             'sync_integration_tests.isolate',
           ],
           'sources': [
             'sync_integration_tests.isolate',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }