Revert "Add mac_window_server_killers to browser_tests data on Mac."

This reverts commit f09f52a1.

Reason for revert: yet another friendly lesson on the dangers of notry.

Original change's description:
> Add mac_window_server_killers to browser_tests data on Mac.
> 
> TBR=ellyjones@chromium.org,liaoyuke@chromium.org
> 
> Bug: 828031
> Change-Id: Ie98ee83cee2d4c98c29a2ac1290728da5b87c4a7
> No-Try: True
> Reviewed-on: https://chromium-review.googlesource.com/1028482
> Reviewed-by: John Budorick <jbudorick@chromium.org>
> Commit-Queue: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#553626}

TBR=ellyjones@chromium.org,liaoyuke@chromium.org,jbudorick@chromium.org

Change-Id: Ida00d9ae602b301008a0bdaab46255c2361c6107
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 828031
Reviewed-on: https://chromium-review.googlesource.com/1028491Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553696}

chrome/test/BUILD.gn

@@ -1883,8 +1883,6 @@ test("browser_tests") {
         "../browser/process_singleton_browsertest.cc",
       ]
 
-      data += [ "mac_window_server_killers.browser_tests.filter" ]
-
       if (safe_browsing_mode == 1) {
         sources -= [
           # single-process mode hangs on Mac sometimes because of multiple UI