In setSourceAreaCaret(), use feature detection rather than browser sniffing, and avoid using deprecated dojo/_base/window::global attribute.   The code to set the caret (both before and after my change) doesn't seem to work on chrome though.  Also, it's hardly ever called; only when the editor is programatically focused.  Refs #9745 !strict.
Replace global use of deprecated dojo/_base/window::global with "window", since win.global always evaluates to window when there is no enclosing withGlobal() method.  Refs #15216 !strict.
Update comment to match changes in [30674], refs #15216 !strict.
When converting stylesheet relative URL's to absolute URL's, use "location" from Editor.ownerDocument.parentWindow, rather than from dojo/_base/window::global.   This is mainly for consistency with the other changes in #15216, and to avoid use of the likely-to-be-deprecated dojo/_base/window::global variable.  I'm sure I could have also just used the global "window" variable also.   Refs #15216 !strict.