Disable failing animations test on mac10.13

TBR=alancutter@chromium.org
NOTRY=true

Bug: 854053
Change-Id: Ie4264d2c95790c028a3054a385975a8c49192ed0
Reviewed-on: https://chromium-review.googlesource.com/1105525Reviewed-by: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Commit-Queue: Giovanni Ortuño Urquidi <ortuno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568338}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4748,3 +4748,4 @@ crbug.com/853360 [ Mac ] fast/forms/select/menulist-appearance-rtl.html [ Failur
 
 # Sheriff 2018-06-18
 crbug.com/853852 [ Linux ] virtual/threaded/external/wpt/feature-policy/experimental-features/vertical-scroll-wheel-block-manual.tentative.html [ Pass Timeout ]
+crbug.com/854053 [ Mac10.13 Debug ] virtual/threaded/fast/animationworklet/animation-worklet-scroll-timeline.html [ Pass Crash ]