Disable flakey test on Slimming Paint V2.

virtual/threaded/fast/animationworklet/animation-worklet-scroll-timeline.html

is very broken with SPv2.

TBR=majidvp@chromium.org

Bug: 778875
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2
Change-Id: Ic94109ad74c09dfcbc48f4bf44a3ba134fda0918
Reviewed-on: https://chromium-review.googlesource.com/802637Reviewed-by: James MacLean <wjmaclean@chromium.org>
Commit-Queue: James MacLean <wjmaclean@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520952}

third_party/WebKit/LayoutTests/FlagExpectations/enable-slimming-paint-v2

@@ -1439,6 +1439,7 @@ crbug.com/702365 virtual/threaded/animations/composited-filter-webkit-filter.htm
 crbug.com/702370 virtual/threaded/animations/compositor-independent-transform-cancel.html [ Failure ]
 crbug.com/778875 virtual/threaded/fast/animationworklet/animation-worklet-visual-update.html [ Failure Crash ]
 crbug.com/778875 virtual/threaded/fast/animationworklet/animation-worklet-animator-animate.html [ Failure ]
+crbug.com/778875 virtual/threaded/fast/animationworklet/animation-worklet-scroll-timeline.html [ Failure ]
 
 # Eight of the frames in the test below paint no content. In SPv2 we will never
 # composite animations that paint nothing. For now we mark this test as failing,