Move dataset attribute from Element to HTMLElement / SVGElement as per the specifications:
Firefox and Chrome seem to have dataset on HTMLElement but not on SVGElement.
See also discussion at https://github.com/whatwg/dom/issues/280
Created attachment 285830 [details]
Comment on attachment 285830 [details]
Clearing flags on attachment: 285830
Committed r204377: <http://trac.webkit.org/changeset/204377>
All reviewed patches have been landed. Closing bug.