virtual/implsidepainting/inspector/timeline/timeline-dom-content-loaded-event.html crashes

BUG=298188
TBR=caseq

Review URL: https://codereview.chromium.org/148443007

git-svn-id: svn://svn.chromium.org/blink/trunk@166278 bbb929c8-8fbe-4397-9dbb-9b2b20218538