[Editor] Don't set as active an editor which is not (bug 1781763)
[Editor] Don't set as active an editor which is not (bug 1781763)

timvandermeij/pdf.js,timvandermeij/pdf.js,showpad/mozilla-pdf.js,Snuffleupagus/pdf.js,Shoobx/pdf.js,Shoobx/pdf.js,showpad/mozilla-pdf.js,mozilla/pdf.js,mozilla/pdf.js,mozilla/pdf.js,timvandermeij/pdf.js,Shoobx/pdf.js,Snuffleupagus/pdf.js,Snuffleupagus/pdf.js,showpad/mozilla-pdf.js