buildbot: disable windowserver killer suite

TBR=jbudorick@chromium.org

Bug: 828031
Change-Id: I9b82139d30a9ae9b4071292d16adb64cd17255e6
Reviewed-on: https://chromium-review.googlesource.com/1049828Reviewed-by: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556780}

testing/buildbot/filters/mac_window_server_killers.browser_tests.filter

 # https://crbug.com/828031
 
 # Suites implicated in window_server deaths.
-# -ConstrainedWebDialogBrowserTest.BasicTest
--ConstrainedWebDialogBrowserTest.ReleaseWebContents
--ConstrainedWebDialogBrowserTest.ContentResizeInAutoResizingDialog
--ConstrainedWebDialogBrowserTest.ContentResizeInNonAutoResizingDialog
+-ConstrainedWebDialogBrowserTest.*