The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/7ceb7d256797dfa18b074e062cd982ab2d202b32

commit 7ceb7d256797dfa18b074e062cd982ab2d202b32
Author: Xida Chen <xidachen@chromium.org>
Date: Tue Apr 24 12:10:41 2018

Mark two animation-type layout tests crash on Mac10.11 debug bot

TBR=smcgruer@chromium.org
NOTRY=true

Bug:  836185 
Change-Id: I0f31be6d2638556bf6b734e6d8f03f1fd7eb4b19
Reviewed-on: https://chromium-review.googlesource.com/1025318
Reviewed-by: Xida Chen <xidachen@chromium.org>
Commit-Queue: Xida Chen <xidachen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553053}
[modify] https://crrev.com/7ceb7d256797dfa18b074e062cd982ab2d202b32/third_party/WebKit/LayoutTests/TestExpectations

This is  issue 816534 , which was a bad CSS fast-path bit of code. I have a CL up to fix it, but having trouble getting it current for submit over all these TestExpectation changes. :p

Strange that this didn't show on Mac 10.11 debug before; it's already disabled on Mac 10.12 debug (and all other debug builds) for the same reason...