Remove fake UserGestureIndicator from WebLocalFrameImpl

This CL removes the old code needed to make the blink roll happen properly.

This is part 3 of 3, depends on:
https://codereview.chromium.org/518583003/

BUG=408426, 406336

Review URL: https://codereview.chromium.org/518633002

git-svn-id: svn://svn.chromium.org/blink/trunk@181660 bbb929c8-8fbe-4397-9dbb-9b2b20218538