Gardening: provide custom expectations for virtual/implsidepainting/inspector/timeline/timeline-paint.html

BUG=
TBR= ojan, tasak

Review URL: https://codereview.chromium.org/281453004

git-svn-id: svn://svn.chromium.org/blink/trunk@173849 bbb929c8-8fbe-4397-9dbb-9b2b20218538