https://bugs.webkit.org/show_bug.cgi?id=92000

Implements the text-decoration shorthand (with -webkit- prefix), as specified by the CSS3 Text Decoration specification:
http://dev.w3.org/csswg/css-text-decor-3/#text-decoration-property

Backported from Blink:
https://src.chromium.org/viewvc/blink?revision=156266&view=revision

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@154338 268f45cc-cd09-0410-ab3c-d52691b4dbfc