Initial call to webkitRequestAnimationFrame returns 0, Spec indicates the handle should always be > 0
https://bugs.webkit.org/show_bug.cgi?id=85819

Reviewed by James Robinson.

Source/WebCore:

The callback id returned by requestAnimationFrame was beginning at zero, when the spec
says it should be above one. Use a pre-increment rather than a post-increment.

Test: fast/animation/request-animation-frame-callback-id.html

* dom/ScriptedAnimationController.cpp:
(WebCore::ScriptedAnimationController::registerCallback): Pre-increment rather than post-increment.

LayoutTests:

* fast/animation/request-animation-frame-callback-id-expected.txt: Added.
* fast/animation/request-animation-frame-callback-id.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@125633 268f45cc-cd09-0410-ab3c-d52691b4dbfc