Gardening: virtual/implsidepainting/inspector/timeline/timeline-auto-record.html,timeline-decode-resize.html times out on Mac

BUG=372213
TBR=ojan, reed@google.com
NOTRY=true

Review URL: https://codereview.chromium.org/276343002

git-svn-id: svn://svn.chromium.org/blink/trunk@173866 bbb929c8-8fbe-4397-9dbb-9b2b20218538