[iOS] Pinching into a video (fullscreen gesture) leaves page zoomed in
https://bugs.webkit.org/show_bug.cgi?id=134433
<rdar://problem/16630794>

Reviewed by Eric Carlson.

Detect the number of target touches (those directly on the
video element) and disable the page zoom if it looks
like the user is trying to trigger fullscreen.

* Modules/mediacontrols/mediaControlsiOS.js:
(ControllerIOS.prototype.handleBaseGestureStart): If we are seeing
two touches in this video element, don't trigger fullscreen. The
exception is if we haven't yet started playback.
(ControllerIOS.prototype.handleBaseGestureChange): Don't allow fullscreen
if we haven't started playback (iOS 7 behaviour).
(ControllerIOS.prototype.handleWrapperTouchStart): Keep track of the
number of targetted touches.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@170572 268f45cc-cd09-0410-ab3c-d52691b4dbfc