Mark some layout tests as failing.

Bug: 764179, 764180
Tbr: benwells@chromium.org
Change-Id: I29c80af68e40186b814f4f215f96e25c4206ceb6
Reviewed-on: https://chromium-review.googlesource.com/662259
Commit-Queue: Ben Wells <benwells@chromium.org>
Reviewed-by: Ben Wells <benwells@chromium.org>
Cr-Commit-Position: refs/heads/master@{#501182}

third_party/WebKit/LayoutTests/TestExpectations

@@ -3667,3 +3667,7 @@ crbug.com/763208 [ Linux ] virtual/mojo-loading/http/tests/devtools/sources/debu
 crbug.com/763809 [ Win7 Debug ] fast/multicol/nested-very-tall-inside-short-crash.html [ Pass Failure Timeout ]
 crbug.com/763810 [ Win7 Debug ] virtual/threaded/transitions/transition-end-event-nested.html [ Pass Failure ]
 crbug.com/763975 [ Linux Debug ] webaudio/internals/cycle-connection-gc.html [ Pass Failure ]
+
+# Sheriff failures 2017-09-12
+crbug.com/764179 [ Mac10.11 ] virtual/gpu-rasterization/images/color-profile-background-image-space.html [ Pass Failure ]
+crbug.com/764180 [ Android ] virtual/display_list_2d_canvas/fast/canvas/script-inside-canvas-fallback.html [ Pass Crash ]