Update test expectations for

rootscroller/gesture-scroll-document-not-root-scroller.html

Bug: 900730
Change-Id: I4cff47211412225bf84a74cd8574afe97fdd470b
TBR: zmin@chromium.org
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/1311091Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#604376}

third_party/WebKit/LayoutTests/TestExpectations

@@ -5588,3 +5588,4 @@ crbug.com/900356 [ Win ] virtual/threaded/animations/animationworklet/worklet-an
 crbug.com/900326 [ Win7 Mac10.12 ] http/tests/devtools/network/preview-searchable.js [ Timeout Pass ]
 crbug.com/900641 [ Linux ] compositing/transitions/transform-on-large-layer.html [ Timeout Pass ]
 crbug.com/900703 external/wpt/cors/origin.htm [ Failure Pass ]
+crbug.com/900730 [ Mac ] rootscroller/gesture-scroll-document-not-root-scroller.html [ Pass Failure Timeout Crash ]
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