We would like to have an callback just before AuthorShadowRoot is aded. it will be used for Bug 77936, Bug 90532, Bug 77937, etc.
Created attachment 152100 [details] Patch
Comment on attachment 152100 [details] Patch Please mention that bug id
Created attachment 152103 [details] Patch for landing
Committed r122530: <http://trac.webkit.org/changeset/122530>