v8: Remove dependency on xdisplaycheck

BUG=670470
R=dpranke@chromium.org

Review-Url: https://codereview.chromium.org/2544053002
Cr-Commit-Position: refs/heads/master@{#41460}

tools/mb/mb.py

@@ -1014,7 +1014,6 @@ class MetaBuildWrapper(object):
                  + logdog_command + test_cmdline)
     elif use_x11 and test_type == 'windowed_test_launcher':
       extra_files = [
-          'xdisplaycheck',
           '../../testing/test_env.py',
           '../../testing/xvfb.py',
       ]