Clear contentEditable selection when it can't be drawn
Clear contentEditable selection when it can't be drawn

So that we don't leave a stray selection that'll be reset
to some nonsense position by the DOM changes.

Closes #4625

notepadqq/CodeMirror,ejgallego/CodeMirror,grzegorzmazur/CodeMirror,jkaplon/CodeMirror,namin/CodeMirror,hackmdio/CodeMirror,ejgallego/CodeMirror,notepadqq/CodeMirror,mtaran-google/CodeMirror,dperetti/CodeMirror,jkaplon/CodeMirror,wingify/CodeMirror,ficristo/CodeMirror,nightwing/CodeMirror,MarcelGerber/CodeMirror,SidPresse/CodeMirror,nightwing/CodeMirror,wingify/CodeMirror,MarcelGerber/CodeMirror,schanzer/CodeMirror,codio/CodeMirror,thomasjm/CodeMirror,mtaran-google/CodeMirror,ficristo/CodeMirror,schanzer/CodeMirror,pabloferz/CodeMirror,kerabromsmu/CodeMirror,jayaprabhakar/CodeMirror,nightwing/CodeMirror,kerabromsmu/CodeMirror,dperetti/CodeMirror,codio/CodeMirror,thomasjm/CodeMirror,ficristo/CodeMirror,jkaplon/CodeMirror,grzegorzmazur/CodeMirror,namin/CodeMirror,hackmdio/CodeMirror,namin/CodeMirror,ejgallego/CodeMirror,SidPresse/CodeMirror,thomasjm/CodeMirror,jayaprabhakar/CodeMirror,hackmdio/CodeMirror,kerabromsmu/CodeMirror,pabloferz/CodeMirror,grzegorzmazur/CodeMirror,jayaprabhakar/CodeMirror,SidPresse/CodeMirror,wingify/CodeMirror,pabloferz/CodeMirror,MarcelGerber/CodeMirror,dperetti/CodeMirror,schanzer/CodeMirror,mtaran-google/CodeMirror,notepadqq/CodeMirror,codio/CodeMirror