Remove redundant checks from WebInputEvent::isGestureEventType
https://bugs.webkit.org/show_bug.cgi?id=112503

Reviewed by Darin Fisher.

GesturePinchBegin, GesturePinchEnd and GesturePinchUpdate were checked
for twice.

This was found by experimenting with a potential new Clang warning.

* public/WebInputEvent.h:
(WebKit::WebInputEvent::isGestureEventType):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146003 268f45cc-cd09-0410-ab3c-d52691b4dbfc