Mark virtual/scroll_customization/fast/events/touch/touch-latched-scroll-node-removed.html flaky

Another recent flake was in
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Mac10.13%20%28retina%29/1633

TBR=sahel@chromium.org

Bug: 869726
Change-Id: I8822f4fb53a2c762ddbb46f66ba307b3803b765d
Reviewed-on: https://chromium-review.googlesource.com/1179836Reviewed-by: Friedrich Horschig <fhorschig@chromium.org>
Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584063}

third_party/WebKit/LayoutTests/TestExpectations

@@ -4965,6 +4965,9 @@ crbug.com/874737 [ Android ] animations/stability/empty-keyframes.html [ Crash ]
 crbug.com/874737 [ Android ] animations/svg-attribute-composition/svg-bias-composition.html [ Crash ]
 crbug.com/874737 [ Android ] animations/svg-attribute-interpolation/svg-numOctaves-interpolation.html [ Crash ]
 
+# Sheriff 2018-08-17
+crbug.com/869726 [ Mac ] virtual/scroll_customization/fast/events/touch/touch-latched-scroll-node-removed.html [ Pass Failure ]
+
 # Test frequently times out on Mac CQ bots.
 crbug.com/874703 [ Mac ] http/tests/devtools/extensions/extensions-panel.js [ Timeout Pass ]