Sign in front of keyframe selector causes stylesheet parsing to abort
https://bugs.webkit.org/show_bug.cgi?id=96844

Patch by Glenn Adams <glenn@skynav.com> on 2012-09-30
Reviewed by Simon Fraser.

Source/WebCore:

Allow optional unary operator (+|-) on PERCENTAGE in keyframe selector.

Test: animations/keyframe-selector-negative-percentage.html

* css/CSSGrammar.y:
Add maybe_unary_operator to PERCENTAGE on keyframe selector. Negative keyframe
selector value is already ignored in StyleKeyframe::parseKeyString.

LayoutTests:

Add test case for correct handling of negative percentage in keyframe selector.

* animations/keyframe-selector-negative-percentage-expected.txt: Added.
* animations/keyframe-selector-negative-percentage.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk/LayoutTests@130007 268f45cc-cd09-0410-ab3c-d52691b4dbfc