getComputedStyle of flex-item-align:auto should resolve to it's parent's flex-align...

getComputedStyle of flex-item-align:auto should resolve to it's parent's flex-align value
https://bugs.webkit.org/show_bug.cgi?id=76326

Reviewed by Tony Chang.

Source/WebCore:

* css/CSSComputedStyleDeclaration.cpp:
(WebCore::CSSComputedStyleDeclaration::getPropertyCSSValue):

LayoutTests:

* css3/flexbox/css-properties-expected.txt:
* platform/chromium-win/fast/css/getComputedStyle/computed-style-expected.txt:
* platform/chromium-win/fast/css/getComputedStyle/computed-style-without-renderer-expected.txt:
* platform/chromium-win/svg/css/getComputedStyle-basic-expected.txt:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107833 268f45cc-cd09-0410-ab3c-d52691b4dbfc