Revert "Bug 1024993 - Update CSS xfail list to be green"

This reverts commit dade090fc3299af85a19b5930d4720c203c3e43e.
Revert "Bug 1024993 -  Run the CSS Linter in Travis/TBPL"

This reverts commit 6afc2da504ecccd4c0906a2f7fed962b0163535b.