Fix ES6-ism in addon
Fix ES6-ism in addon

hackmdio/CodeMirror,notepadqq/CodeMirror,jkaplon/CodeMirror,mtaran-google/CodeMirror,wingify/CodeMirror,jayaprabhakar/CodeMirror,namin/CodeMirror,notepadqq/CodeMirror,mtaran-google/CodeMirror,ficristo/CodeMirror,SidPresse/CodeMirror,ficristo/CodeMirror,pabloferz/CodeMirror,pabloferz/CodeMirror,rrandom/CodeMirror,ejgallego/CodeMirror,rrandom/CodeMirror,kerabromsmu/CodeMirror,schanzer/CodeMirror,rrandom/CodeMirror,nightwing/CodeMirror,schanzer/CodeMirror,jayaprabhakar/CodeMirror,notepadqq/CodeMirror,thomasjm/CodeMirror,namin/CodeMirror,ficristo/CodeMirror,MarcelGerber/CodeMirror,dperetti/CodeMirror,ejgallego/CodeMirror,MarcelGerber/CodeMirror,grzegorzmazur/CodeMirror,jkaplon/CodeMirror,hackmdio/CodeMirror,nightwing/CodeMirror,mtaran-google/CodeMirror,kerabromsmu/CodeMirror,nightwing/CodeMirror,wingify/CodeMirror,SidPresse/CodeMirror,schanzer/CodeMirror,thomasjm/CodeMirror,grzegorzmazur/CodeMirror,codio/CodeMirror,hackmdio/CodeMirror,codio/CodeMirror,grzegorzmazur/CodeMirror,jkaplon/CodeMirror,SidPresse/CodeMirror,crazy4chrissi/CodeMirror,dperetti/CodeMirror,MarcelGerber/CodeMirror,crazy4chrissi/CodeMirror,namin/CodeMirror,codio/CodeMirror,crazy4chrissi/CodeMirror,dperetti/CodeMirror,pabloferz/CodeMirror,ejgallego/CodeMirror,jayaprabhakar/CodeMirror,thomasjm/CodeMirror,kerabromsmu/CodeMirror,wingify/CodeMirror