Gardening: crashing layout tests

The following tests are crashing on debug builds:
virtual/gpu/fast/canvas/webgl/gl-object-get-calls.html
fast/canvas/webgl/gl-object-get-calls.html

Chromium blame list: 218302:218309
Blink blame list: 156335

TBR=dominicc@chromium.org
BUG=276031

Review URL: https://codereview.chromium.org/23205012

git-svn-id: svn://svn.chromium.org/blink/trunk@156344 bbb929c8-8fbe-4397-9dbb-9b2b20218538