[CSS Shapes] shape-outside animation does not handle 'auto' well
https://bugs.webkit.org/show_bug.cgi?id=125700

Reviewed by Dirk Schulze.

Source/WebCore:

Handle the case where we are blending/animating with a null ShapeValue due to 'auto'.

Adapted LayoutTests/fast/shapes/shape-outside-floats/shape-outside-animation.html for testing this.

* page/animation/CSSPropertyAnimation.cpp:
(WebCore::blendFunc):

LayoutTests:

Test a shape-outside animation where one keyframe uses 'auto'.

* fast/shapes/shape-outside-floats/shape-outside-animation-expected.txt:
* fast/shapes/shape-outside-floats/shape-outside-animation.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@160623 268f45cc-cd09-0410-ab3c-d52691b4dbfc