Remove RuntimeEnabledFeature for DirectWrite

Controlled by explicit API now, per
https://codereview.chromium.org/210243004 and must land after https://codereview.chromium.org/212953007/ .

R=eae@chromium.org, jamesr@chromium.org
BUG=333029

Review URL: https://codereview.chromium.org/213173003

git-svn-id: svn://svn.chromium.org/blink/trunk@170242 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Keep the user gesture when postMessage() across frames.

R=adamk@chromium.org
BUG=355658,178319,161068

Review URL: https://codereview.chromium.org/209363002

git-svn-id: svn://svn.chromium.org/blink/trunk@170243 bbb929c8-8fbe-4397-9dbb-9b2b20218538