Image.__proto__ should be Function.prototype, not HTMLElement.prototype, as per: - https://heycam.github.io/webidl/#named-constructors Gecko and Blink agree with the specification.
Created attachment 351430 [details] Patch
Created attachment 351438 [details] Patch
Comment on attachment 351438 [details] Patch Clearing flags on attachment: 351438 Committed r236769: <https://trac.webkit.org/changeset/236769>
All reviewed patches have been landed. Closing bug.
<rdar://problem/44956798>