vertical-align may apply to :first-line selector but is not required by the spec.
More info:
http://lists.w3.org/Archives/Public/public-css-testsuite/2013Oct/0000.html
http://wiki.csswg.org/spec/css2.1#issue-216

Therefore, first-line-pseudo-012, 013 and 014 now have the "may"
flag.