auto merge of #4187 : cgaebel/servo/issue-4127, r=SimonSapin
auto merge of #4187 : cgaebel/servo/issue-4127, r=SimonSapin

This will avoid drawing Arcs if there's no border-radius property set.

Fixes #4127 

codemac/servo,youprofit/servo,codemac/servo,caldwell/servo,peterjoel/servo,boghison/servo,notriddle/servo,wartman4404/servo,dhananjay92/servo,samfoo/servo,g-k/servo,karlito40/servo,tschneidereit/servo,SimonSapin/servo,fiji-flo/servo,jgraham/servo,nick-thompson/servo,snf/servo,jgraham/servo,dagnir/servo,runarberg/servo,dmarcos/servo,g-k/servo,boghison/servo,meh/servo,dati91/servo,eddyb/servo,snf/servo,bjwbell/servo,brendandahl/servo,dati91/servo,mdibaiee/servo,anthgur/servo,meh/servo,nnethercote/servo,jimberlage/servo,ruud-v-a/servo,tafia/servo,mattnenterprise/servo,boghison/servo,pyfisch/servo,steveklabnik/servo,mbrubeck/servo,zhangjunlei26/servo,luniv/servo,larsbergstrom/servo,mt2d2/servo,snf/servo,snf/servo,rnestler/servo,kindersung/servo,DominoTree/servo,caldwell/servo,echochamber/servo,eddyb/servo,RenaudParis/servo,aidanhs/servo,paulrouget/servo,emilio/servo,vks/servo,indykish/servo,splav/servo,boghison/servo,jgraham/servo,caldwell/servo,nnethercote/servo,dati91/servo,akosel/servo,ryancanhelpyou/servo,caldwell/servo,DominoTree/servo,nnethercote/servo,karlito40/servo,jlegendary/servo,rentongzhang/servo,rixrix/servo,vks/servo,snf/servo,sadmansk/servo,saneyuki/servo,tafia/servo,zhangjunlei26/servo,splav/servo,notriddle/servo,mt2d2/servo,anthgur/servo,KiChjang/servo,larsbergstrom/servo,sadmansk/servo,ConnorGBrewster/servo,rentongzhang/servo,saratang/servo,notriddle/servo,steveklabnik/servo,aweinstock314/servo,aidanhs/servo,peterjoel/servo,tschneidereit/servo,froydnj/servo,thiagopnts/servo,jimberlage/servo,brendandahl/servo,canaltinova/servo,indykish/servo,ConnorGBrewster/servo,WriterOfAlicrow/servo,splav/servo,luniv/servo,DominoTree/servo,j3parker/servo,jimberlage/servo,bjwbell/servo,pyecs/servo,WriterOfAlicrow/servo,nerith/servo,canaltinova/servo,cbrewster/servo,dagnir/servo,eddyb/servo,ryancanhelpyou/servo,GreenRecycleBin/servo,g-k/servo,cbrewster/servo,pyecs/servo,dati91/servo,thiagopnts/servo,upsuper/servo,splav/servo,larsbergstrom/servo,notriddle/servo,hyowon/servo,evilpie/servo,huonw/servo,AnthonyBroadCrawford/servo,larsbergstrom/servo,AnthonyBroadCrawford/servo,dvberkel/servo,szeged/servo,jdramani/servo,deokjinkim/servo,ryancanhelpyou/servo,wpgallih/servo,splav/servo,evilpie/servo,sadmansk/servo,fiji-flo/servo,meh/servo,paulrouget/servo,AnthonyBroadCrawford/servo,jgraham/servo,srbhklkrn/SERVOENGINE,rentongzhang/servo,dsandeephegde/servo,ConnorGBrewster/servo,fiji-flo/servo,SimonSapin/servo,tempbottle/servo,luniv/servo,KiChjang/servo,rixrix/servo,szeged/servo,vks/servo,nerith/servo,GreenRecycleBin/servo,mbrubeck/servo,anthgur/servo,mbrubeck/servo,thiagopnts/servo,dmarcos/servo,mdibaiee/servo,KiChjang/servo,nrc/servo,s142857/servo,SimonSapin/servo,vks/servo,indykish/servo,akosel/servo,pgonda/servo,zentner-kyle/servo,srbhklkrn/SERVOENGINE,dagnir/servo,aweinstock314/servo,echochamber/servo,dagnir/servo,brendandahl/servo,zhangjunlei26/servo,ConnorGBrewster/servo,pyfisch/servo,SimonSapin/servo,DominoTree/servo,mbrubeck/servo,jimberlage/servo,wpgallih/servo,j3parker/servo,huonw/servo,WriterOfAlicrow/servo,nrc/servo,zhangjunlei26/servo,jlegendary/servo,jdramani/servo,dsandeephegde/servo,A-deLuna/servo,kindersung/servo,meh/servo,ryancanhelpyou/servo,dati91/servo,jimberlage/servo,s142857/servo,cbrewster/servo,anthgur/servo,vks/servo,CJ8664/servo,notriddle/servo,echochamber/servo,srbhklkrn/SERVOENGINE,jdramani/servo,peterjoel/servo,WriterOfAlicrow/servo,sadmansk/servo,ruud-v-a/servo,j3parker/servo,saratang/servo,nick-thompson/servo,emilio/servo,GreenRecycleBin/servo,szeged/servo,youprofit/servo,SimonSapin/servo,A-deLuna/servo,aidanhs/servo,jlegendary/servo,tempbottle/servo,fiji-flo/servo,szeged/servo,mattnenterprise/servo,peterjoel/servo,nrc/servo,pyfisch/servo,bjwbell/servo,mattnenterprise/servo,cbrewster/servo,jlegendary/servo,dati91/servo,rixrix/servo,dagnir/servo,aweinstock314/servo,wartman4404/servo,KiChjang/servo,vks/servo,tschneidereit/servo,ConnorGBrewster/servo,peterjoel/servo,pyfisch/servo,dsandeephegde/servo,samfoo/servo,walac/servo,rixrix/servo,indykish/servo,evilpie/servo,emilio/servo,Adenilson/prototype-viewing-distance,WriterOfAlicrow/servo,tempbottle/servo,AnthonyBroadCrawford/servo,nnethercote/servo,runarberg/servo,pyfisch/servo,dmarcos/servo,sadmansk/servo,codemac/servo,notriddle/servo,szeged/servo,zentner-kyle/servo,paulrouget/servo,aidanhs/servo,zhangjunlei26/servo,pyecs/servo,codemac/servo,deokjinkim/servo,tempbottle/servo,srbhklkrn/SERVOENGINE,rnestler/servo,aweinstock314/servo,WriterOfAlicrow/servo,GreenRecycleBin/servo,DominoTree/servo,samfoo/servo,canaltinova/servo,srbhklkrn/SERVOENGINE,larsbergstrom/servo,emilio/servo,meh/servo,Adenilson/prototype-viewing-distance,chotchki/servo,ruud-v-a/servo,tschneidereit/servo,zentner-kyle/servo,dvberkel/servo,GyrosOfWar/servo,szeged/servo,j3parker/servo,RenaudParis/servo,rnestler/servo,rixrix/servo,brendandahl/servo,KiChjang/servo,GreenRecycleBin/servo,hyowon/servo,hyowon/servo,saratang/servo,karlito40/servo,avadacatavra/servo,saratang/servo,pyfisch/servo,jimberlage/servo,indykish/servo,jlegendary/servo,avadacatavra/servo,caldwell/servo,tempbottle/servo,walac/servo,s142857/servo,dvberkel/servo,youprofit/servo,dsandeephegde/servo,walac/servo,dhananjay92/servo,samfoo/servo,akosel/servo,eddyb/servo,hyowon/servo,huonw/servo,thiagopnts/servo,g-k/servo,GyrosOfWar/servo,dmarcos/servo,mbrubeck/servo,paulrouget/servo,wpgallih/servo,eddyb/servo,notriddle/servo,mattnenterprise/servo,splav/servo,canaltinova/servo,pyecs/servo,nick-thompson/servo,larsbergstrom/servo,pyfisch/servo,peterjoel/servo,SimonSapin/servo,samfoo/servo,mt2d2/servo,mt2d2/servo,anthgur/servo,rnestler/servo,chotchki/servo,deokjinkim/servo,avadacatavra/servo,mdibaiee/servo,dsandeephegde/servo,CJ8664/servo,pyfisch/servo,zhangjunlei26/servo,luniv/servo,meh/servo,dmarcos/servo,hyowon/servo,CJ8664/servo,zhangjunlei26/servo,zentner-kyle/servo,nerith/servo,DominoTree/servo,emilio/servo,codemac/servo,mdibaiee/servo,walac/servo,KiChjang/servo,dvberkel/servo,luniv/servo,dsandeephegde/servo,wpgallih/servo,canaltinova/servo,splav/servo,ryancanhelpyou/servo,echochamber/servo,avadacatavra/servo,kindersung/servo,anthgur/servo,GreenRecycleBin/servo,kindersung/servo,dagnir/servo,aidanhs/servo,evilpie/servo,paulrouget/servo,indykish/servo,szeged/servo,mbrubeck/servo,ruud-v-a/servo,WriterOfAlicrow/servo,youprofit/servo,tafia/servo,RenaudParis/servo,evilpie/servo,walac/servo,paulrouget/servo,huonw/servo,s142857/servo,youprofit/servo,ruud-v-a/servo,canaltinova/servo,akosel/servo,tempbottle/servo,GyrosOfWar/servo,steveklabnik/servo,dvberkel/servo,ConnorGBrewster/servo,karlito40/servo,dmarcos/servo,saneyuki/servo,dvberkel/servo,froydnj/servo,evilpie/servo,Adenilson/prototype-viewing-distance,boghison/servo,eddyb/servo,DominoTree/servo,rentongzhang/servo,chotchki/servo,runarberg/servo,rixrix/servo,cbrewster/servo,mattnenterprise/servo,KiChjang/servo,GreenRecycleBin/servo,saratang/servo,cbrewster/servo,snf/servo,mdibaiee/servo,froydnj/servo,nrc/servo,rnestler/servo,froydnj/servo,nnethercote/servo,GyrosOfWar/servo,fiji-flo/servo,zhangjunlei26/servo,j3parker/servo,Adenilson/prototype-viewing-distance,codemac/servo,jimberlage/servo,bjwbell/servo,aweinstock314/servo,zentner-kyle/servo,paulrouget/servo,peterjoel/servo,eddyb/servo,zhangjunlei26/servo,wartman4404/servo,wpgallih/servo,Adenilson/prototype-viewing-distance,notriddle/servo,fiji-flo/servo,srbhklkrn/SERVOENGINE,pgonda/servo,paulrouget/servo,dsandeephegde/servo,splav/servo,jgraham/servo,A-deLuna/servo,RenaudParis/servo,jgraham/servo,g-k/servo,fiji-flo/servo,KiChjang/servo,indykish/servo,indykish/servo,rentongzhang/servo,karlito40/servo,ConnorGBrewster/servo,g-k/servo,AnthonyBroadCrawford/servo,SimonSapin/servo,zentner-kyle/servo,evilpie/servo,vks/servo,runarberg/servo,tafia/servo,tschneidereit/servo,RenaudParis/servo,peterjoel/servo,chotchki/servo,pgonda/servo,larsbergstrom/servo,bjwbell/servo,szeged/servo,nerith/servo,nrc/servo,meh/servo,chotchki/servo,steveklabnik/servo,walac/servo,pyfisch/servo,jdramani/servo,srbhklkrn/SERVOENGINE,snf/servo,upsuper/servo,aweinstock314/servo,echochamber/servo,froydnj/servo,sadmansk/servo,nick-thompson/servo,saneyuki/servo,nnethercote/servo,saneyuki/servo,nick-thompson/servo,emilio/servo,notriddle/servo,ryancanhelpyou/servo,steveklabnik/servo,runarberg/servo,samfoo/servo,karlito40/servo,nick-thompson/servo,caldwell/servo,ConnorGBrewster/servo,runarberg/servo,kindersung/servo,pyecs/servo,chotchki/servo,tschneidereit/servo,mdibaiee/servo,ruud-v-a/servo,splav/servo,upsuper/servo,peterjoel/servo,deokjinkim/servo,rnestler/servo,GreenRecycleBin/servo,avadacatavra/servo,saneyuki/servo,dhananjay92/servo,codemac/servo,brendandahl/servo,zentner-kyle/servo,bjwbell/servo,pyecs/servo,jlegendary/servo,GyrosOfWar/servo,s142857/servo,s142857/servo,dhananjay92/servo,dagnir/servo,A-deLuna/servo,mdibaiee/servo,anthgur/servo,youprofit/servo,GyrosOfWar/servo,RenaudParis/servo,thiagopnts/servo,huonw/servo,canaltinova/servo,wartman4404/servo,tschneidereit/servo,dhananjay92/servo,wpgallih/servo,pgonda/servo,jimberlage/servo,echochamber/servo,tafia/servo,tafia/servo,rnestler/servo,avadacatavra/servo,dhananjay92/servo,KiChjang/servo,DominoTree/servo,aidanhs/servo,nnethercote/servo,dsandeephegde/servo,nerith/servo,paulrouget/servo,pgonda/servo,CJ8664/servo,nnethercote/servo,cbrewster/servo,hyowon/servo,akosel/servo,nrc/servo,CJ8664/servo,dvberkel/servo,aidanhs/servo,bjwbell/servo,Adenilson/prototype-viewing-distance,rixrix/servo,wpgallih/servo,deokjinkim/servo,saneyuki/servo,emilio/servo,samfoo/servo,nick-thompson/servo,luniv/servo,pgonda/servo,A-deLuna/servo,saneyuki/servo,emilio/servo,g-k/servo,cbrewster/servo,steveklabnik/servo,upsuper/servo,GreenRecycleBin/servo,hyowon/servo,pgonda/servo,upsuper/servo,jdramani/servo,larsbergstrom/servo,steveklabnik/servo,mt2d2/servo,wartman4404/servo,jdramani/servo,tafia/servo,youprofit/servo,luniv/servo,larsbergstrom/servo,splav/servo,indykish/servo,nrc/servo,mattnenterprise/servo,rnestler/servo,upsuper/servo,KiChjang/servo,rentongzhang/servo,thiagopnts/servo,eddyb/servo,froydnj/servo,j3parker/servo,Adenilson/prototype-viewing-distance,wpgallih/servo,dati91/servo,rixrix/servo,mt2d2/servo,wartman4404/servo,mattnenterprise/servo,caldwell/servo,notriddle/servo,saratang/servo,boghison/servo,CJ8664/servo,mt2d2/servo,larsbergstrom/servo,rentongzhang/servo,ryancanhelpyou/servo,kindersung/servo,SimonSapin/servo,avadacatavra/servo,s142857/servo,pyecs/servo,saneyuki/servo,pyfisch/servo,dmarcos/servo,akosel/servo,nerith/servo,DominoTree/servo,CJ8664/servo,emilio/servo,mbrubeck/servo,tempbottle/servo,paulrouget/servo,deokjinkim/servo,A-deLuna/servo,deokjinkim/servo,walac/servo,saneyuki/servo,jlegendary/servo,mbrubeck/servo,dhananjay92/servo,kindersung/servo,brendandahl/servo,echochamber/servo,akosel/servo,szeged/servo,upsuper/servo,CJ8664/servo,jimberlage/servo,mattnenterprise/servo,nnethercote/servo,emilio/servo,sadmansk/servo,rixrix/servo,nerith/servo,AnthonyBroadCrawford/servo,thiagopnts/servo,evilpie/servo,fiji-flo/servo,jgraham/servo,jdramani/servo,huonw/servo,wpgallih/servo,evilpie/servo,saneyuki/servo,peterjoel/servo,AnthonyBroadCrawford/servo,canaltinova/servo,karlito40/servo,runarberg/servo,boghison/servo,saratang/servo,j3parker/servo,aweinstock314/servo,A-deLuna/servo,upsuper/servo,szeged/servo,DominoTree/servo,anthgur/servo,wartman4404/servo,thiagopnts/servo,RenaudParis/servo,sadmansk/servo,dati91/servo,huonw/servo,avadacatavra/servo,GyrosOfWar/servo,nnethercote/servo,brendandahl/servo