Rebaseline visibility-image-layers for the winxp and win7 in virtual/threaded. Also add a few flaky tests to TestExpectations.

BUG=
TBR=gavinp@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/498253002

git-svn-id: svn://svn.chromium.org/blink/trunk@180850 bbb929c8-8fbe-4397-9dbb-9b2b20218538