Revert of Remove WebSettings::setDisallowFullscreenForNonMediaElements(bool) (https://codereview.chromium.org/416013002/)

Reason for revert:
We need this for the Android WebView

Original issue's description:
> Remove WebSettings::setDisallowFullscreenForNonMediaElements(bool)
> 
> It is never called from Chromium.
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=178831

TBR=jochen@chromium.org,qinmin@chromium.org,philipj@opera.com
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/422923002

git-svn-id: svn://svn.chromium.org/blink/trunk@179048 bbb929c8-8fbe-4397-9dbb-9b2b20218538