use data-dojo-attach-point rather than dojoAttachPoint, refs #16585

git-svn-id: http://svn.dojotoolkit.org/src/dijit/trunk@31405 560b804f-0ae3-0310-86f3-f6aa0a117693
(cherry picked from commit cf32a1023c0a31cd8eeca1e5ac7d456299d35e3c)
Fix tabbing through Fieldset widget on chrome and safari.

Webkit is buggy with tabstops on <legend> nodes so switch focusNode to the
<span> inside the <legend>.

Fixes #17428.

(cherry picked from commit 1a124a2adfbaaedefa335e2e87aee23652132e22)
fix Fieldset's aria-labelledby attribute, fixes #18009

(cherry picked from commit 7979c25dc5778c3af43e0ca6d72a1451bca6ea9c)