LayoutTests: Mark a few tests in compositing/gestures/ as flaky

These were enabled at crrev.com/c/1121786 but still a few tests are failing on
Mac10.10 Tests bot.

TBR=pdr@chromium.org
NOTRY=true

Bug: 857501
Change-Id: I20542f3c38550de579db0304c9d27be8e67e5cc8
Reviewed-on: https://chromium-review.googlesource.com/1124729Reviewed-by: Makoto Shimazu <shimazu@chromium.org>
Commit-Queue: Makoto Shimazu <shimazu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572411}

third_party/WebKit/LayoutTests/TestExpectations

@@ -95,6 +95,11 @@ crbug.com/816045 [ Win Linux Mac ] virtual/gpu/fast/canvas/canvas-imageSmoothing
 # seem to fix it.
 crbug.com/309675 compositing/gestures/gesture-tapHighlight-simple-longPress.html [ Failure ]
 
+# These are failing only on Mac10.10 Tests bot.
+crbug.com/857501 [ Mac ] compositing/gestures/gesture-tapHighlight-pixel-rotated-div.html [ Failure Pass ]
+crbug.com/857501 [ Mac ] compositing/gestures/gesture-tapHighlight-pixel-rotated-link.html [ Failure Pass ]
+crbug.com/857501 [ Mac ] compositing/gestures/gesture-tapHighlight-pixel-transparent.html [ Failure Pass ]
+
 crbug.com/845267 [ Mac ] http/tests/inspector-protocol/page/page-lifecycleEvents.js [ Failure Pass ]
 
 # SwiftShader Failures