Fix corner case in measureChar
Fix corner case in measureChar

In IE, measuring in a hidden editor would cause a null deref
because getClientRects returned an empty array.

Issue #2095

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