Suppress flakes in doubletap-to-jump-forwards-too-short.html.

Suppressing flakes in the following layout test:

  virtual/modern-media-controls/media/controls/modern/
    doubletap-to-jump-forwards-too-short.html

Tbr: steimel@chromium.org
Bug: 831720
Change-Id: Id8975175c8a0001e433cdcc693b340170a5036c2
Reviewed-on: https://chromium-review.googlesource.com/1007976Reviewed-by: Kenneth Russell <kbr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549992}

third_party/WebKit/LayoutTests/TestExpectations

@@ -3813,6 +3813,9 @@ crbug.com/783154 [ Mac ] virtual/modern-media-controls/media/controls/modern/dou
 crbug.com/783154 [ Mac ] virtual/modern-media-controls/media/controls/modern/doubletap-on-play-button.html [ Skip ]
 crbug.com/783154 [ Mac ] virtual/modern-media-controls/media/controls/modern/doubletap-to-toggle-fullscreen.html [ Skip ]
 
+# Seen flaky on Linux, suppressing on Windows as well
+crbug.com/831720 [ Win Linux ] virtual/modern-media-controls/media/controls/modern/doubletap-to-jump-forwards-too-short.html [ Pass Failure ]
+
 crbug.com/802915 css3/blending/isolation-should-include-non-local-background.html [ Failure ]
 
 crbug.com/807838 external/wpt/service-workers/service-worker/worker-in-sandboxed-iframe-by-csp-fetch-event.https.html [ Crash Pass ]