Disable one fullscreen layout test

virtual/android/fullscreen/api/document-exit-fullscreen-vs-request.html
is flaky on chromium.linux bots, because of recent change of user
activation is consumed for fullscreen, disable it for now, we will fix
once we confirm this change will be accepted.
https://analysis.chromium.org/p/chromium/flake-portal/analysis/culprit?key=ag9zfmZpbmRpdC1mb3ItbWVyQwsSDEZsYWtlQ3VscHJpdCIxY2hyb21pdW0vNzZjYTRlMDhjYzJiYWJlZWI2YzlmOGMwYWU2MjFjYzYxNTdmMTcwMgw

Bug: 852645
Change-Id: Idd8799adf603f45c2e6c1de94cef8824c7de83c9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1636820Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Commit-Queue: Lan Wei <lanwei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665141}

third_party/blink/web_tests/TestExpectations

@@ -4318,6 +4318,7 @@ crbug.com/831509 virtual/navigation-mojo-response/external/wpt/service-workers/s
 crbug.com/852645 external/wpt/fullscreen/api/element-request-fullscreen-twice-manual.html [ Failure ]
 crbug.com/852645 external/wpt/fullscreen/api/element-request-fullscreen-two-elements-manual.html [ Failure ]
 crbug.com/852645 external/wpt/fullscreen/api/element-request-fullscreen-two-iframes-manual.html [ Failure Timeout ]
+crbug.com/852645 virtual/android/fullscreen/api/document-exit-fullscreen-vs-request.html [ Failure ]
 
 # Sheriff failures 2017-02-21
 crbug.com/73609 http/tests/media/video-play-stall.html [ Pass Timeout ]