Mark paint/invalidation/table/table-hover-on-link.html as flaky on Linux

TBR=wangxianzhu@chromium.org

Bug: 839734
Change-Id: Ic35abab341a46e52d2586f2f5515bf0701f96fec
Reviewed-on: https://chromium-review.googlesource.com/1043985Reviewed-by: Marc Treib <treib@chromium.org>
Commit-Queue: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#556025}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4686,3 +4686,7 @@ crbug.com/836783 fast/peerconnection/RTCRtpSender-setParameters.html [ Pass Time
 crbug.com/838254 virtual/video-surface-layer/media/webkit-media-controls-webkit-appearance.html [ Failure ]
 
 crbug.com/839332 [ Mac ] virtual/video-surface-layer/media/video-no-audio.html [ Pass Failure ]
+
+# Sheriff 2018-05-04
+crbug.com/839734 [ Linux ] paint/invalidation/table/table-hover-on-link.html [ Pass Failure ]
+crbug.com/839734 [ Linux ] virtual/disable-spv175/paint/invalidation/table/table-hover-on-link.html [ Pass Failure ]