Mark paint/invalidation/window-resize/ flakily timeout

Bug: 919789
Change-Id: Ib608c65039661778affb35bb1d892b7a62bf81aa
Reviewed-on: https://chromium-review.googlesource.com/c/1485021Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634946}

third_party/blink/web_tests/TestExpectations

@@ -375,6 +375,8 @@ crbug.com/836886 compositing/overflow/scaled-overflow.html [ Failure ]
 crbug.com/836886 compositing/scrollbars/nested-overlay-scrollbars.html [ Failure ]
 # Flaky subpixel AA difference (not necessarily incorrect, but flaky)
 crbug.com/921105 virtual/threaded/animations/skew-notsequential-compositor.html [ Failure Pass ]
+# Occasionally timeout, but the test coverage is still good
+crbug.com/919789 paint/invalidation/window-resize/ [ Timeout Pass ]
 
 # ====== Paint team owned tests to here ======
 
@@ -5809,7 +5811,6 @@ crbug.com/719023 media_capabilities/encodingInfo-avc1.html [ Pass Failure ]
 
 # Sheriff 2019-01-07
 crbug.com/919492 [ Mac ] virtual/fractional_scrolling_threaded/fast/scrolling/overflow-scrollability.html [ Timeout Pass ]
-crbug.com/919504 paint/invalidation/window-resize/window-resize-vertical-writing-mode.html [ Timeout Pass ]
 crbug.com/919559 [ Win ] virtual/outofblink-cors/http/tests/fetch/window/thorough/redirect-loop.html [ Timeout Pass ]
 crbug.com/919587 [ Linux ] virtual/threaded/fast/idle-callback/idle_periods.html [ Pass Failure ]