Fix drag-and-drop in IE9
Fix drag-and-drop in IE9

Closes #373

leoshine/CodeMirror,ZombieHippie/CodeMirror,Allenice/CodeMirror,CartoDB/CodeMirror,matthewbauer/CodeMirror,jochenberger/CodeMirror,Carreau/CodeMirror,jayaprabhakar/CodeMirror,mtaran-google/CodeMirror,kolya-ay/CodeMirror,jochenberger/CodeMirror,trumanliu/CodeMirror,thomasjm/CodeMirror,agendor/CodeMirror,thomasjm/CodeMirror,amshali/CodeMirror,happibum/CodeMirror-main,dudb/CodeMirror,ashmind/CodeMirror,flyskyko/CodeMirror,jessegrosjean/CodeMirror,dudb/CodeMirror,hccampos/CodeMirror,kangkot/CodeMirror,nawroth/CodeMirror,Ermlab/CodeMirror,Dominator008/CodeMirror,crazy4chrissi/CodeMirror,dbarnett/CodeMirror,INTELOGIE/CodeMirror,rustemferreira/CodeMirror,camellhf/CodeMirror,cben/CodeMirror,davidpham87/CodeMirror,trumanliu/CodeMirror,sgoo/CodeMirror,isdampe/CodeMirror,ksanaforge/CodeMirror,jessegrosjean/CodeMirror,AlanWasTaken/codemirror,qweasd1/CodeMirror,femhub/CodeMirror2,DustinH/CodeMirror,Icenium/CodeMirror,amireh/codemirror,sanyaade-iot/CodeMirror,ficristo/CodeMirror,michaelerobertsjr/CodeMirror,trumanliu/CodeMirror,angelozerr/CodeMirror,fivetran/CodeMirror,Allenice/CodeMirror,notepadqq/CodeMirror,supriyantomaftuh/CodeMirror,mizchi/CodeMirror,schanzer/CodeMirror,InternetGuru/CodeMirror,Navaneethsen/CodeMirror,namin/CodeMirror,adobe/CodeMirror2,melpon/CodeMirror,cintiamh/CodeMirror,sekcheong/CodeMirror,kuangyeheng/CodeMirror,codio/CodeMirror,NumbersInternational/CodeMirror,shiren/CodeMirror,hccampos/CodeMirror,pjkui/CodeMirror,TDaglis/CodeMirror,vincentwoo/CodeMirror,pabloferz/CodeMirror,rrandom/CodeMirror,karthikeyansam/CodeMirror,SidPresse/CodeMirror,tpphu/CodeMirror,buchslava/CodeMirror,MarcelGerber/CodeMirror,rustemferreira/CodeMirror,xeronith/CodeMirror,flyskyko/CodeMirror,wbinnssmith/CodeMirror,NumbersInternational/CodeMirror,sanyaade-iot/CodeMirror,apatawari/CodeMirror,TDaglis/CodeMirror,elisee/CodeMirror,djadmin/CodeMirror,isdampe/CodeMirror,webida/CodeMirror,jhnesk/CodeMirror,rrandom/CodeMirror,webida/CodeMirror,loopspace/CodeMirror,INTELOGIE/CodeMirror,kuangyeheng/CodeMirror,gkoberger/CodeMirror,ashmind/CodeMirror,Aliccer/CodeMirror,vanloswang/CodeMirror,kk9599/CodeMirror,sourcelair/CodeMirror,karthikeyansam/CodeMirror,jpolitz/CodeMirror,Dominator008/CodeMirror,anthonygego/CodeMirror,systay/CodeMirror,camellhf/CodeMirror,sanyaade-iot/CodeMirror,kevinushey/CodeMirror,ZombieHippie/CodeMirror,Icenium/CodeMirror,manderson23/CodeMirror,filonb/CodeMirror2,ZombieHippie/CodeMirror,NumbersInternational/CodeMirror,belph/CodeMirror,bocharsky-bw/CodeMirror,belph/CodeMirror,buchslava/CodeMirror,symbla/CodeMirror,grzegorzmazur/CodeMirror,nightwing/CodeMirror,AlanWasTaken/codemirror,SidPresse/CodeMirror,fmoliveira/CodeMirror,anthonygego/CodeMirror,ejgallego/CodeMirror,belph/CodeMirror,jkaplon/CodeMirror,EasonYi/CodeMirror,kevinushey/CodeMirror,ThebingServices/CodeMirror,kangkot/CodeMirror,pinbe/CodeMirror,EasonYi/CodeMirror,systay/CodeMirror,dperetti/CodeMirror,fmoliveira/CodeMirror,r7kamura/CodeMirror,loopspace/CodeMirror,djadmin/CodeMirror,hackmdio/CodeMirror,shiren/CodeMirror,fpco/codemirror,systay/CodeMirror,karthikeyansam/CodeMirror,wingify/CodeMirror,d0liver/CodeMirror,Icenium/CodeMirror,jkaplon/CodeMirror,wingify/CodeMirror,kerabromsmu/CodeMirror,nawroth/CodeMirror,vanloswang/CodeMirror,skylarkcob/CodeMirror,KamranMackey/CodeMirror,webida/CodeMirror,pabloferz/CodeMirror,AlanWasTaken/codemirror,hackmdio/CodeMirror,bluesh55/CodeMirror,vincentwoo/CodeMirror,TDaglis/CodeMirror,nawroth/CodeMirror,InternetGuru/CodeMirror,kerabromsmu/CodeMirror,ssxxue/CodeMirror,pinbe/CodeMirror,hackmdio/CodeMirror,TechnicalPursuit/CodeMirror,sekcheong/CodeMirror,antimatter15/CodeMirror,symbla/CodeMirror,ssxxue/CodeMirror,crazy4chrissi/CodeMirror,CartoDB/CodeMirror,notepadqq/CodeMirror,NeZaMy/CodeMirror2,InternetGuru/CodeMirror,vanloswang/CodeMirror,jansel/CodeMirror,agendor/CodeMirror,Jisuanke/CodeMirror,NeZaMy/CodeMirror2,pjkui/CodeMirror,qiankun007/CodeMirror,codio/CodeMirror,pjkui/CodeMirror,Carreau/CodeMirror,elisee/CodeMirror,TechnicalPursuit/CodeMirror,camellhf/CodeMirror,crazy4chrissi/CodeMirror,manderson23/CodeMirror,philuchansky/CodeMirror,angelozerr/CodeMirror,mtaran-google/CodeMirror,MarcelGerber/CodeMirror,qweasd1/CodeMirror,increpare/CodeMirror,karevn/CodeMirror,dperetti/CodeMirror,sgoo/CodeMirror,jpolitz/CodeMirror,joshterrell805-historic/CodeMirror,joshterrell805-historic/CodeMirror,loopspace/CodeMirror,EasonYi/CodeMirror,bfrohs/CodeMirror,bfrohs/CodeMirror,r7kamura/CodeMirror,kuangyeheng/CodeMirror,rasata/CodeMirror,ThebingServices/CodeMirror,mightyguava/CodeMirror,skylarkcob/CodeMirror,leoshine/CodeMirror,dperetti/CodeMirror,dbarnett/CodeMirror,morrisonwudi/CodeMirror,happibum/CodeMirror-main,kangkot/CodeMirror,namin/CodeMirror,sourcelair/CodeMirror,mizchi/CodeMirror,agendor/CodeMirror,filonb/CodeMirror2,buchslava/CodeMirror,femhub/CodeMirror2,jessegrosjean/CodeMirror,mtaran-google/CodeMirror,karevn/CodeMirror,tpphu/CodeMirror,bgrins/CodeMirror,Navaneethsen/CodeMirror,michaelerobertsjr/CodeMirror,fivetran/CodeMirror,skylarkcob/CodeMirror,explorigin/CodeMirror,nightwing/CodeMirror,thomasjm/CodeMirror,supriyantomaftuh/CodeMirror,rasata/CodeMirror,grzegorzmazur/CodeMirror,ficristo/CodeMirror,axter/CodeMirror,mihailik/CodeMirror,dbarnett/CodeMirror,bluesh55/CodeMirror,schanzer/CodeMirror,bocharsky-bw/CodeMirror,jayaprabhakar/CodeMirror,michaelerobertsjr/CodeMirror,apatawari/CodeMirror,webida/CodeMirror,sekcheong/CodeMirror,codio/CodeMirror,matthewbauer/CodeMirror,GerHobbelt/CodeMirror2,increpare/CodeMirror,melpon/CodeMirror,morrisonwudi/CodeMirror,wingify/CodeMirror,amshali/CodeMirror,mihailik/CodeMirror,sourcelair/CodeMirror,vincentwoo/CodeMirror,ksanaforge/CodeMirror,cintiamh/CodeMirror,DustinH/CodeMirror,jpolitz/CodeMirror,rrandom/CodeMirror,antimatter15/CodeMirror,ksanaforge/CodeMirror,fpco/codemirror,wbinnssmith/CodeMirror,KamranMackey/CodeMirror,fmoliveira/CodeMirror,elisee/CodeMirror,abdelouahabb/CodeMirror,manderson23/CodeMirror,ThebingServices/CodeMirror,cben/CodeMirror,kerabromsmu/CodeMirror,adobe/CodeMirror2,jansel/CodeMirror,explorigin/CodeMirror,pabloferz/CodeMirror,NeZaMy/CodeMirror2,gkoberger/CodeMirror,nightwing/CodeMirror,adobe/CodeMirror2,axter/CodeMirror,SidPresse/CodeMirror,matthewbauer/CodeMirror,karevn/CodeMirror,MarcelGerber/CodeMirror,Navaneethsen/CodeMirror,DustinH/CodeMirror,d0liver/CodeMirror,alur/CodeMirror,hccampos/CodeMirror,alur/CodeMirror,xeronith/CodeMirror,Dominator008/CodeMirror,melpon/CodeMirror,xeronith/CodeMirror,TechnicalPursuit/CodeMirror,bluesh55/CodeMirror,amsul/CodeMirror,alur/CodeMirror,KamranMackey/CodeMirror,bgrins/CodeMirror,qiankun007/CodeMirror,isdampe/CodeMirror,pinbe/CodeMirror,ashmind/CodeMirror,amshali/CodeMirror,qiankun007/CodeMirror,apatawari/CodeMirror,philuchansky/CodeMirror,rustemferreira/CodeMirror,kk9599/CodeMirror,notepadqq/CodeMirror,symbla/CodeMirror,kk9599/CodeMirror,dudb/CodeMirror,Jisuanke/CodeMirror,mightyguava/CodeMirror,flyskyko/CodeMirror,cintiamh/CodeMirror,djadmin/CodeMirror,Aliccer/CodeMirror,ejgallego/CodeMirror,bgrins/CodeMirror,happibum/CodeMirror-main,Ermlab/CodeMirror,supriyantomaftuh/CodeMirror,jhnesk/CodeMirror,ejgallego/CodeMirror,davidpham87/CodeMirror,abdelouahabb/CodeMirror,jayaprabhakar/CodeMirror,rasata/CodeMirror,ssxxue/CodeMirror,femhub/CodeMirror2,morrisonwudi/CodeMirror,mightyguava/CodeMirror,davidpham87/CodeMirror,bocharsky-bw/CodeMirror,GerHobbelt/CodeMirror2,bfrohs/CodeMirror,antimatter15/CodeMirror,increpare/CodeMirror,Aliccer/CodeMirror,gkoberger/CodeMirror,namin/CodeMirror,kolya-ay/CodeMirror,INTELOGIE/CodeMirror,qweasd1/CodeMirror,mihailik/CodeMirror,axter/CodeMirror,r7kamura/CodeMirror,Allenice/CodeMirror,d0liver/CodeMirror,abdelouahabb/CodeMirror,anthonygego/CodeMirror,grzegorzmazur/CodeMirror,Jisuanke/CodeMirror,shiren/CodeMirror,filonb/CodeMirror2,mizchi/CodeMirror,amsul/CodeMirror,schanzer/CodeMirror,tpphu/CodeMirror,philuchansky/CodeMirror,jkaplon/CodeMirror,ficristo/CodeMirror