Gardening: media/controls/buttons-after-reset.html is flaky

A virtual test was already marked as flaky, but the root test itself
is also flaky.

Bug: 910452
Change-Id: I579264a4b6ef4bab235028d1bce46ceeded8481d
TBR: mlamouri
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/1355309Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Matt Falkenhagen <falken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612543}

third_party/blink/web_tests/TestExpectations

@@ -4988,8 +4988,9 @@ crbug.com/794338 [ Android ] virtual/video-surface-layer/media/video-rotation.ht
 crbug.com/811605 media/video-poster-after-loadedmetadata.html [ Failure Pass ]
 crbug.com/811605 virtual/video-surface-layer/media/video-poster-after-loadedmetadata.html [ Failure Pass ]
 
+crbug.com/910452 media/controls/buttons-after-reset.html [ Pass Failure ]
+
 crbug.com/860368 virtual/video-surface-layer/media/autoplay/webaudio-audio-context-resume.html  [ Pass Failure ]
-crbug.com/860368 virtual/video-surface-layer/media/controls/buttons-after-reset.html [ Pass Failure ]
 crbug.com/860368 virtual/video-surface-layer/media/controls/captions-menu-always-visible.html [ Pass Failure ]
 crbug.com/860368 virtual/video-surface-layer/media/controls/paint-controls-webkit-appearance-none-custom-bg.html [ Pass Failure ]
 crbug.com/860368 virtual/video-surface-layer/media/controls/paint-controls-webkit-appearance-none.html [ Pass Failure ]