Remove the unnecessary close_tab in display_EdidStress test

This test does not open any new tab. Don't need to close_tab method
at the end.

BUG=None
TEST=Ran display_EdidStress test passed.

Change-Id: Ib438f783c40f66149146ba6ab8d16c8f3a982f6a
Reviewed-on: https://chromium-review.googlesource.com/233570
Reviewed-by: Kalin Stoyanov <kalin@chromium.org>
Commit-Queue: Wai-Hong Tam <waihong@chromium.org>
Tested-by: Wai-Hong Tam <waihong@chromium.org>
1 file changed