Fixed popup warning of unsaved page (=cancelling edit of page when setting "Warn me when I leave an edit page with unsaved changes" in users preferences has been enabled). Dialog appears only with Cancel- button and is disabled with Save-, Preview- and Diff- buttons. IE required fix also with togglelink. Merged '5425cf564d254e520a605e74c61a4266d25a7379' from CKeditor_v4.