Support for Microsoft Edge from Windows build 15002 and up (#6789)
* eventHandler.shouldAcceptEvent: As Windows.UI.Core windows no longer will be a descendant of the foreground window in Edge (and soon to be other UWP apps), for these windows, ensure the window is equal to or a descendant of the active window in the current input thread.
* eventHandler.shouldAcceptEvent: allow all events from Windows.UI.Core windows, as Edge, and soon to be all UWP apps, will no longer have their windows as a descendant of the foreground window.
* Allow matching of the root of Edge documents by seeing if its parent is not marked as being in a framework of MicrosoftEdge, rather than only seeing if the document is inside an EdgeRootContainer.
This change is necessary for Windows builds 15002 and up where the root container is now gone.
* Edge: ensure we don't go into an endless recursion when fetching text with fields due to a collapsed range due to the range from an enclosing element ending on or before this range. Quite common in Edge builds once the 'gap' is removed.
