Re-enable custom elements API in Safari Technology Preview not that we've updated our implementation. Also see the bug 159829 which disabled this feature in Safari Technology Preview.
Created attachment 287709 [details] Re-enables the feature
I'm gonna wait for https://bugs.webkit.org/show_bug.cgi?id=161480 and a few other bugs to be fixed.
Bravo! great work Ryosuke!🎉🎉
Comment on attachment 287709 [details] Re-enables the feature I've fixed all the major bugs now.
<rdar://problem/28176569>
Thanks for the review!
Comment on attachment 287709 [details] Re-enables the feature Clearing flags on attachment: 287709 Committed r205527: <http://trac.webkit.org/changeset/205527>
All reviewed patches have been landed. Closing bug.