[ChromeDriver] Implement SwitchToFrame by element command.

chrome/test/chromedriver/run_py_tests.py

 #!/usr/bin/env python
 # 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.
 
 """End to end tests for ChromeDriver."""
 
 import ctypes
 import optparse
 import os
@@ skipping 82 matching lines @@
     self._driver.SwitchToFrame('id')
     self.assertTrue(self._driver.ExecuteScript('return window.top != window'))
     self._driver.SwitchToMainFrame()
     self.assertTrue(self._driver.ExecuteScript('return window.top == window'))
     self._driver.SwitchToFrame('name')
     self.assertTrue(self._driver.ExecuteScript('return window.top != window'))
     self._driver.SwitchToMainFrame()
     self.assertTrue(self._driver.ExecuteScript('return window.top == window'))
     self._driver.SwitchToFrameByIndex(0)
     self.assertTrue(self._driver.ExecuteScript('return window.top != window'))
+    self._driver.SwitchToMainFrame()
+    self.assertTrue(self._driver.ExecuteScript('return window.top == window'))
+    self._driver.SwitchToFrame(self._driver.FindElement('tag name', 'iframe'))
+    self.assertTrue(self._driver.ExecuteScript('return window.top != window'))
 
   def testExecuteInRemovedFrame(self):
     self._driver.ExecuteScript(
         'var frame = document.createElement("iframe");'
         'frame.id="id";'
         'frame.name="name";'
         'document.body.appendChild(frame);'
         'window.addEventListener("message",'
         '    function(event) { document.body.removeChild(frame); });')
     self.assertTrue(self._driver.ExecuteScript('return window.top == window'))
@@ skipping 193 matching lines @@
   global _ANDROID_PACKAGE
   _ANDROID_PACKAGE = options.android_package
 
   all_tests_suite = unittest.defaultTestLoader.loadTestsFromModule(
       sys.modules[__name__])
   tests = unittest_util.FilterTestSuite(all_tests_suite, options.filter)
   ChromeDriverTest.GlobalSetUp()
   result = unittest.TextTestRunner().run(tests)
   ChromeDriverTest.GlobalTearDown()
   sys.exit(len(result.failures) + len(result.errors))