Evt.target is not set for native events on IE6-8, so need to use evt.srcElement instead.  Fixes regression in dojo/tests/on/on from [30051], refs #15097 and fixes #16543 !strict.
Second try to get dojo/ready and dojo/domReady! to play nice together.   dojo/ready still needs to yield to any tasks registered via domReady(), but callbacks in the dojo/ready queue cannot be removed until they are ready to be run.   Fixes #16389 !strict.   Needed to add some hooks into the dojo/domReady code so that dojo/ready can yield to tasks in that queue, but they can be removed for 2.0.
change API doc for indexOf() and lastIndexOf() to say that it's using == not ===, refs #16104 !strict