Use is<>() / downcast<>() for SpinButtonElement instead of isSpinButtonElement() / static_cast.
Created attachment 240149 [details] Patch
Created attachment 240151 [details] Patch
Comment on attachment 240151 [details] Patch LGTM.
Comment on attachment 240151 [details] Patch Clearing flags on attachment: 240151 Committed r174917: <http://trac.webkit.org/changeset/174917>
All reviewed patches have been landed. Closing bug.