Disable flaky virtual/threaded/fast/scroll-behavior/wheel-and-touch-scroll-use-count.html on Linux.

TBR=sahel@chromium.org

Bug: 899715
Change-Id: Ic6b90ce68432b2f1254740e237d32f674fa3e628
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/1303366Reviewed-by: Henrik Grunell <grunell@chromium.org>
Commit-Queue: Henrik Grunell <grunell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#603469}

third_party/WebKit/LayoutTests/TestExpectations

@@ -5736,3 +5736,4 @@ crbug.com/899232 [ Linux ] virtual/user-activation-v2/fast/events/touch/gesture/
 
 # Sheriff 2018-10-29
 crbug.com/899710 [ Linux ] virtual/threaded/http/tests/devtools/tracing/timeline-paint/timeline-paint-with-layout-invalidations.js [ Failure Pass ]
+crbug.com/899715 [ Linux ] virtual/threaded/fast/scroll-behavior/wheel-and-touch-scroll-use-count.html [ Failure Pass ]