Anchor, Area & Link elements no longer matches :enabled

HTML spec has been modified [1] to disable support for :enabled CSS
selector on Anchor, Area & Link elements, after discussion on W3C
Bugzilla [2].

[1] https://html5.org/r/8818
[2] https://www.w3.org/Bugs/Public/show_bug.cgi?id=26622
Merge pull request #1263 from brunoabinader/css-selector-pseudo-class-enabled

Anchor, Area & Link elements no longer matches :enabled; r=Ms2ger