Remove incorrect custom expectation for fast/form/autofilled on mac.

TBR=tkent@chromium.org,ziran.sun@samsung.com
NOTRY=true

Review URL: https://codereview.chromium.org/603483002

git-svn-id: svn://svn.chromium.org/blink/trunk@182576 bbb929c8-8fbe-4397-9dbb-9b2b20218538