Refactoring code to make opening from !DropDownButton via keyboard (space/enter key) work on IE8:    - make _HasDropDown setup handlers on the focusNode, rather than domNode (simply by removing _buttonNode attach point), so that those handlers are isolated from the hidden <input> (which also fires a click event), and so the handlers still fire even though the ondijitclick code does a evt.preventDefault()    - connect to onkeydown rather than onkeypress since the ondijitclick's evt.preventDefault() call (in the onkeydown handler) cancels the onkeypress event on IE8.
Refactoring code to make opening from !DropDownButton via keyboard (space/enter key) work on IE8:
   - make _HasDropDown setup handlers on the focusNode, rather than domNode (simply by removing _buttonNode attach point), so that those handlers are isolated from the hidden <input> (which also fires a click event), and so the handlers still fire even though the ondijitclick code does a evt.preventDefault()
   - connect to onkeydown rather than onkeypress since the ondijitclick's evt.preventDefault() call (in the onkeydown handler) cancels the onkeypress event on IE8.

Fixes #11040, refs #11003.


git-svn-id: 674a2d6b1e32e53f607eb824547723f32280967e@21981 560b804f-0ae3-0310-86f3-f6aa0a117693

Sam-Cummins/delite,harbalk/delite,kitsonk/delite,kitsonk/delite,Sam-Cummins/delite,harbalk/delite