Implement accessibility for dialog

[Becky Gibson]

The dialog box needs to be updated for accessibility.

-set the containing element to have a waiRole of dialog with the title attribute of that element set to the name of the dialog. Note that there may still be some screen reader issues with this so "dialog" may not be spoken even after the role has been properly set.

-contain the tab sequence within the dialog (make it modal)- this is not completely working yet. once the user tabs through all of the elements focus should go back to the first element - it should cycle within the dialog until the dialog is dismissed. Currently it goes around once and then ends up back into address bar of browser and can never be returned to dialog via keyboard.

-When the dialog is displayed set focus to the appropriate element on the page (this is likely the first focusable element but could be author defined if we want to add that parameter to the dialog widget).

• ESC key to exit dialog

[bill]

Becky, you should assign this to someone on your team, right? Dialog code is checked in now so I think it's ready to be made accessible.

[Becky Gibson]

since this just appeared on June 4 - making 0.9 beta will depend upon the date. The a11y team lost quite a few cycles on the theme change.

[Becky Gibson]

(In [9197]) refs #2505; dialog a11y; fix dialog template so dialog events are set properly in order to main focus in dialog; set focus to dialog title when opened - still needs addn css work; added labels to test dialog file

[Becky Gibson]

(In [9220]) refs #2505 - fix dialog.html - tabStart needs tabindex set

[Becky Gibson]

(In [9233]) refs #2505 better handling of modality; use onblur/deactivate event to determine last focusable item in dialog - use that when shift-tabbing to cycle focus to all items; Escape key closes dialog; save and restore focus when dialog closes - fixes #2421

[Becky Gibson]

(In [9241]) update .dijitDialog with padding so setting focus to dialog title does NOT cause horizontal scroll. final a11y changes - fixes #2505