window.HTMLDetailsElement should exist: https://html.spec.whatwg.org/multipage/forms.html#the-details-element The interface does not have [NoInterfaceObject] in the specification but it does in WebKit.
Created attachment 261148 [details] Patch
Comment on attachment 261148 [details] Patch Clearing flags on attachment: 261148 Committed r189762: <http://trac.webkit.org/changeset/189762>
All reviewed patches have been landed. Closing bug.