Adding a UseCounter for DOMWindow.open with and without the feature string.

R=abarth
BUG=82522

Review URL: https://codereview.chromium.org/360083002

git-svn-id: svn://svn.chromium.org/blink/trunk@177249 bbb929c8-8fbe-4397-9dbb-9b2b20218538