[WebIDL] Add support for interface mixins
Created attachment 408095 [details] Patch
Created attachment 408097 [details] Patch
Not sure why svn-apply is only failing on windows, but I think this is none-the-less ready for review.
Created attachment 408110 [details] Patch
Committed r266678: <https://trac.webkit.org/changeset/266678> All reviewed patches have been landed. Closing bug and clearing flags on attachment 408110 [details].
<rdar://problem/68410831>