Dialog: Fix shift-tab handling, focus the correct element

Copy-paste error introduced in df6110c0d424ff3306fdd5576011f2dcf4d242d0

Updates the tabbing test to be more specific about which element should
have focus, instead of only checking if focus is within the dialog.

Ref #9646
Ref #10103
Closes gh-1264
Dialog: Honor preventDefault when managing focus

If event.isDefaultPrevented() is true, the focus management is
completely skipped, assuming the user manages focus manually.

Fixes #10103
Closes gh-1265
#10098 moving disabled tab click handlers onto role=tabpanel elements for better Voiceover announcement
Tabs: all content announced as clickable in VO

moving tab list event bindings for disabled li's from selector
onto this.tablist inside of processTabs().
Adding an unbind call on tab list in destroy() for cleanup