HTMLElement / SVGElement should implement GlobalEventHandlers, not Element: https://html.spec.whatwg.org/multipage/dom.html#htmlelement Firefox and Chrome behave as per the specification. Fixing this also fixes rendering on http://survey123.arcgis.com/ with WebKit ToT.
<rdar://problem/27019299>
And for SVGElement: https://www.w3.org/TR/SVG2/types.html#InterfaceSVGElement
Created attachment 282209 [details] Patch
Comment on attachment 282209 [details] Patch Clearing flags on attachment: 282209 Committed r202539: <http://trac.webkit.org/changeset/202539>
All reviewed patches have been landed. Closing bug.