fix TileLayer.brintToFront/Back on IE6-8, close #1168
fix TileLayer.brintToFront/Back on IE6-8, close #1168

nvoron23/Leaflet,twoubt/Leaflet,tormi/Leaflet,jblarsen/Leaflet,pakro/Leaflet,CorainChicago/Leaflet,juliensoret/Leaflet,tbassett44/Leaflet,elfalem/Leaflet,hyperknot/Leaflet,frafra/ProntoSoccorsoLiguria,geoloep/Leaflet,sambernet/Leaflet,cmulders/Leaflet,bolshoibooze/Leaflet,Leaflet/Leaflet,Andrey-Pavlov/Leaflet,stefanocudini/Leaflet,tyrasd/Leaflet,Trufi/Leaflet,tormi/Leaflet,danzel/Leaflet,AndBicScadMedia/Leaflet,webmechanicx/Leaflet,hyperknot/Leaflet,msiadak/Leaflet,alex2wong/Leaflet,Ossehoht/Leaflet,cartant/Leaflet,nycitt/Leaflet,gabrielpconceicao/frontend-asset-leaflet,pzdz/Leaflet,Srikanth4/Leaflet,elkingtonmcb/Leaflet,nikhildhamsaniya/Leaflet,elfalem/Leaflet,javimolla/Leaflet,DrillingInfo/Leaflet,cmulders/Leaflet,javimolla/Leaflet,snkashis/Leaflet,che603000/Leaflet,devjoseluis/Leaflet,Neorth/Leaflet,wrrnwng/Leaflet,northerneyes/Leaflet,fillerwriter/Leaflet,brunocasanova/frontend-asset-leaflet,Jakobud/Leaflet,thalesfsp/Leaflet,mstahv/Leaflet,dhootha/Leaflet,Mark-Wood/Leaflet,pzdz/Leaflet,northerneyes/Leaflet,litnerdy/Leaflet,Neorth/Leaflet,MuellerMatthew/Leaflet,kjell/Leaflet,w8r/Leaflet,jasonoverland/Leaflet,eriksjaastad/Leaflet,akrzyzanowskino/TeamSE,w8r/Leaflet,grahamthompson/Leaflet,huangsong/Leaflet,olafurr/Leaflet,billybonz1/Leaflet,fredericksilva/Leaflet,sellonen/Leaflet,patrickarlt/Leaflet,iamjonbradley/Leaflet,cmulders/Leaflet,jaropolk2/Leaflet,codeator/Leaflet,rlugojr/Leaflet,nikhildhamsaniya/Leaflet,Srikanth4/Leaflet,jmutua2015/Leaflet,webmechanicx/Leaflet,frogcat/Leaflet,Srikanth4/Leaflet,sisou/Leaflet,billybonz1/Leaflet,lee101/Leaflet,sambernet/Leaflet,frafra/ProntoSoccorsoLiguria,Ubisense/Leaflet,msokk/Leaflet,frogcat/Leaflet,fab1an/Leaflet,akrzyzanowskino/TeamSE,tomnod/Leaflet,Andrey-Pavlov/Leaflet,wancharle/Leaflet,lee101/Leaflet,Ossehoht/Leaflet,akauppi/Leaflet,wrrnwng/Leaflet,starsolaris/Leaflet,hyperknot/Leaflet,RobertoMalatesta/Leaflet,brunocasanova/frontend-asset-leaflet,MuellerMatthew/Leaflet,Ubisense/Leaflet,brah/Leaflet,RLRR/Leaflet,bbecquet/Leaflet,iOffice/Leaflet,davidlukerice/Leaflet,iZucken/Leaflet,jblarsen/Leaflet,codeator/Leaflet,caiiiycuk/Leaflet,tsantacruz/RotationalMarker,Fil/Leaflet,yohanboniface/Leaflet,devjoseluis/Leaflet,nikhildhamsaniya/Leaflet,bolshoibooze/Leaflet,azimux/Leaflet,fredericksilva/Leaflet,sisou/Leaflet,mstahv/Leaflet,jasonoverland/Leaflet,jmutua2015/Leaflet,jasonoverland/Leaflet,iamjonbradley/Leaflet,andrewmartini/Leaflet,Fil/Leaflet,thalesfsp/Leaflet,mediasuitenz/Leaflet,moklick/Leaflet,nathancahill/Leaflet,beni55/Leaflet,brah/Leaflet,psicomante/Leaflet,alex2wong/Leaflet,wpf500/Leaflet,RobertoMalatesta/Leaflet,sambernet/Leaflet,thalesfsp/Leaflet,fredericksilva/Leaflet,bolshoibooze/Leaflet,waeltken/Leaflet,olafurr/Leaflet,CorainChicago/Leaflet,Fil/Leaflet,jmutua2015/Leaflet,RyanHickman/Leaflet,sellonen/Leaflet,waeltken/Leaflet,scaddenp/Leaflet,rlugojr/Leaflet,sellonen/Leaflet,AndBicScadMedia/Leaflet,taraszerebecki/Leaflet,w8r/Leaflet,kumy/Leaflet,brah/Leaflet,taraszerebecki/Leaflet,nathancahill/Leaflet,dhootha/Leaflet,fillerwriter/Leaflet,mbrukman/Leaflet,msiadak/Leaflet,bbecquet/Leaflet,tbassett44/Leaflet,wrrnwng/Leaflet,pakro/Leaflet,elkingtonmcb/Leaflet,davidjb/Leaflet,huangsong/Leaflet,elkingtonmcb/Leaflet,CloudMade/Leaflet,twoubt/Leaflet,fab1an/Leaflet,che603000/Leaflet,gabrielpconceicao/frontend-asset-leaflet,beni55/Leaflet,psicomante/Leaflet,prashen/Leaflet,mediasuitenz/Leaflet,mourner/Leaflet,iamjonbradley/Leaflet,kumy/Leaflet,mbrukman/Leaflet,tomnod/Leaflet,nycitt/Leaflet,DrillingInfo/Leaflet,nkovacs/Leaflet,Leaflet/Leaflet,AP-whitehat/Leaflet,davojta/Leaflet,stefanocudini/Leaflet,nvoron23/Leaflet,litnerdy/Leaflet,AndBicScadMedia/Leaflet,nkovacs/Leaflet,dhootha/Leaflet,lizardtechblog/Leaflet,olafurr/Leaflet,wpf500/Leaflet,andrewmartini/Leaflet,Ossehoht/Leaflet,perliedman/Leaflet,Jakobud/Leaflet,lee101/Leaflet,jblarsen/Leaflet,caiiiycuk/Leaflet,psicomante/Leaflet,kjell/Leaflet,davojta/Leaflet,litnerdy/Leaflet,RLRR/Leaflet,pzdz/Leaflet,2gis/Leaflet,twoubt/Leaflet,yohanboniface/Leaflet,prashen/Leaflet,2gis/Leaflet,grahamthompson/Leaflet,huangsong/Leaflet,nathancahill/Leaflet,billybonz1/Leaflet,Trufi/Leaflet,Trufi/Leaflet,wancharle/Leaflet,Neorth/Leaflet,fab1an/Leaflet,klaftertief/Leaflet,tsantacruz/RotationalMarker,starsolaris/Leaflet,wpf500/Leaflet,eriksjaastad/Leaflet,davojta/Leaflet,bbecquet/Leaflet,srdavis/leaflet-template,cartant/Leaflet,AP-whitehat/Leaflet,fillerwriter/Leaflet,Jakobud/Leaflet,javimolla/Leaflet,codeator/Leaflet,Ubisense/Leaflet,davidlukerice/Leaflet,snkashis/Leaflet,nycitt/Leaflet,scaddenp/Leaflet,msiadak/Leaflet,msokk/Leaflet,stefanocudini/Leaflet,RyanHickman/Leaflet,scaddenp/Leaflet,elfalem/Leaflet,AP-whitehat/Leaflet,waeltken/Leaflet,mstahv/Leaflet,RyanHickman/Leaflet,akauppi/Leaflet,klaftertief/Leaflet,iOffice/Leaflet,akrzyzanowskino/TeamSE,sisou/Leaflet,mourner/Leaflet,frogcat/Leaflet,taraszerebecki/Leaflet,kumy/Leaflet,msokk/Leaflet,prashen/Leaflet,andrewmartini/Leaflet,mediasuitenz/Leaflet,RobertoMalatesta/Leaflet,wancharle/Leaflet,snkashis/Leaflet,CapeSepias/Leaflet,pakro/Leaflet,beni55/Leaflet,cartant/Leaflet,alex2wong/Leaflet,CorainChicago/Leaflet,webmechanicx/Leaflet,rlugojr/Leaflet,eriksjaastad/Leaflet,gabrielpconceicao/frontend-asset-leaflet,geoloep/Leaflet,davidlukerice/Leaflet,iZucken/Leaflet,mourner/Leaflet,geoloep/Leaflet,tormi/Leaflet,devjoseluis/Leaflet,Andrey-Pavlov/Leaflet,grahamthompson/Leaflet,klaftertief/Leaflet,starsolaris/Leaflet,RLRR/Leaflet,juliensoret/Leaflet,iOffice/Leaflet,Mark-Wood/Leaflet,CapeSepias/Leaflet,CapeSepias/Leaflet,mbrukman/Leaflet,tomnod/Leaflet,MuellerMatthew/Leaflet,yohanboniface/Leaflet,patrickarlt/Leaflet,brunocasanova/frontend-asset-leaflet,tbassett44/Leaflet,2gis/Leaflet,caiiiycuk/Leaflet,akauppi/Leaflet,tsantacruz/RotationalMarker,Leaflet/Leaflet,iZucken/Leaflet