Tim Jenssen authored Oct 17, 2017 and Thomas Hartmann committed Oct 18, 2017

 - detaching the TextEditView already emits the TextEditor change signal
   -> so removing the call from QmlDesignerPlugin::deactivateAutoSynchronization()
 - in case the user closed explicit the editor we do not want to emit any
   signals anymore

Change-Id: Idb5c2cdde583f7d32f2a9ef5628d1b6d3fc7bb3f
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>