Remove support for the '-khtml-' and '-apple-' CSS prefixes.

The majority of Blink's support for '-khtml-' and '-apple-' prefixes was removed
in [1] and [2]. Looks like we missed a spot or two.

This CL removes the remaining occurrences from CSSParser-in.cpp and drops the
disabled test that would have tested this behavior.

[1]: https://bugs.webkit.org/show_bug.cgi?id=111890
[2]: https://codereview.chromium.org/13685003

Review URL: https://codereview.chromium.org/30693004

git-svn-id: svn://svn.chromium.org/blink/trunk@160246 bbb929c8-8fbe-4397-9dbb-9b2b20218538