Avoid exception on IE when browser window refocused after switching to another application.   Thanks DaveHS, fixes #16437 !strict.

git-svn-id: http://svn.dojotoolkit.org/src/dijit/trunk@30137 560b804f-0ae3-0310-86f3-f6aa0a117693
(cherry picked from commit 63251cef036907179f528838f131ad1badfdab01)
Fix bad has(ie) checks causing focus issues with Textbox and Editor widgets. Refs #17311.
(cherry picked from commit af80d059f9070bff17e7cbf5c20daa80007d58f0)

Conflicts:
	_editor/RichText.js
Fix bad has(ie) check in IE11 with older versions of focus.js, which invoked attachEvent. Refs #17311.
Clean up notification handles returned from Observable queries. Added condition to test case. Fixes #17394.
(cherry picked from commit bda7e1d7a804b4fd640ef91ae3cbdf94afb49336)

Conflicts:
	form/_FormSelectWidget.js