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

Index: third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
index ed15115c59fb4246bc09c879000911d0e11240ea..d0c6bbd325e86c278c582898714ffe473bc9d302 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/port/linux.py
@@ -188,6 +188,7 @@ class LinuxPort(base.Port):
             _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."""
@@ -219,8 +220,7 @@ class LinuxPort(base.Port):
             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()