Gardening: Layout Test http/tests/security/webgl-remote-read-remote-image-allowed-with-credentials.html is flaky

On win debug, it times out from time to time

BUG=353186
TEST=
TBR=zmo@chromium.org

Review URL: https://codereview.chromium.org/197423004

git-svn-id: svn://svn.chromium.org/blink/trunk@169369 bbb929c8-8fbe-4397-9dbb-9b2b20218538