Reported by https://polymerlabs.github.io/wc-demos/
:host:after and :host:before don't work inside a shadow tree.
Created attachment 294587 [details]
Created attachment 296509 [details]
Note that the patch does not make https://polymerlabs.github.io/wc-demos/ subtest turn green because the test expects slightly different serialization for 'content' (' vs "). Rendering is correct.
Comment on attachment 296509 [details]
Clearing flags on attachment: 296509
Committed r209535: <http://trac.webkit.org/changeset/209535>
All reviewed patches have been landed. Closing bug.