Fix a path through run-webkit-tests where we still aren't getting debugging.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py

 # Copyright (C) 2010 Google Inc. 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
@@ skipping 170 matching lines @@
             # We don't explicitly set the display, as we want to check the
             # environment value.
             exit_code = self.host.executive.run_command(
                 ['xdpyinfo'], return_exit_code=True)
             if exit_code == 0:
                 _log.info('Successfully started Xvfb with display "%s".', display)
                 return
             _log.warn('xdpyinfo check failed with exit code %s while starting Xvfb on "%s".', exit_code, display)
             self.host.sleep(0.1)
         _log.fatal('Failed to start Xvfb on display "%s" (xdpyinfo check failed).', display)
+        self._stop_xvfb()
 
     def _find_display(self):
         """Tries to find a free X display, looping if necessary."""
         # The "xvfb-run" command uses :99 by default.
         for display_number in range(99, 120):
             display = ':%d' % display_number
             exit_code = self.host.executive.run_command(
                 ['xdpyinfo', '-display', display], return_exit_code=True)
             if exit_code == 1:
                 return display
@@ skipping 11 matching lines @@
             self._xvfb_process.kill()
             self._xvfb_process.wait()
         if self._xvfb_stdout and self.host.filesystem.exists(self._xvfb_stdout.name):
             for line in self.host.filesystem.read_text_file(self._xvfb_stdout.name).splitlines():
                 _log.warn('Xvfb stdout:  %s', line)
             self.host.filesystem.remove(self._xvfb_stdout.name)
         if self._xvfb_stderr and self.host.filesystem.exists(self._xvfb_stderr.name):
             for line in self.host.filesystem.read_text_file(self._xvfb_stderr.name).splitlines():
                 _log.warn('Xvfb stderr:  %s', line)
             self.host.filesystem.remove(self._xvfb_stderr.name)
-
-
+        self._xvfb_stdout = self._xvfb_stderr = self._xvfb_process = None
 
     def _path_to_driver(self, target=None):
         binary_name = self.driver_name()
         return self._build_path_with_target(target, binary_name)