Sheriff: disable canvas-lost-gpu-context.html

canvas-lostgpu-context.html is consistently crash in last 3 builds:
https://ci.chromium.org/p/chromium/builders/ci/Mac10.13%20Tests%20%28dbg%29

TBR=thakis@chromium.org

Bug: 818426

Change-Id: I77f658d014ca5eab2bfef811e182e27f1c53ad3b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079681Reviewed-by: Yi Xu <yiyix@chromium.org>
Commit-Queue: Yi Xu <yiyix@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745577}

third_party/blink/web_tests/TestExpectations

@@ -215,7 +215,7 @@ crbug.com/974652 [ Debug ] fast/canvas/OffscreenCanvas-copyImage.html [ Pass Fai
 
 crbug.com/1011060 virtual/gpu/fast/canvas/canvas-getImageData-smooth.html [ Pass Failure ]
 crbug.com/1011060 virtual/gpu/fast/canvas/bug382588.html [ Pass Failure ]
-crbug.com/1011060 virtual/gpu/fast/canvas/canvas-lost-gpu-context.html [ Pass Failure ]
+crbug.com/1011060 virtual/gpu/fast/canvas/canvas-lost-gpu-context.html [ Pass Failure Crash ]
 
 crbug.com/974666 [ Mac10.13 ] http/tests/misc/object-embedding-svg-delayed-size-negotiation-2.htm [ Pass Failure ]
 crbug.com/974720 [ Mac10.13 ] virtual/text-antialias/firstline/capitalize-transform-2.html [ Pass Crash ]