auto merge of #3834 : pcwalton/servo/smallvec-debugging, r=pcwalton
auto merge of #3834 : pcwalton/servo/smallvec-debugging, r=pcwalton

r? @cgaebel 

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inkim/servo,nick-thompson/servo,zentner-kyle/servo,rentongzhang/servo,bfrohs/servo,chotchki/servo,aidanhs/servo,indykish/servo,pgonda/servo,mbrubeck/servo,tschneidereit/servo,samfoo/servo,SimonSapin/servo,tafia/servo,thiagopnts/servo,evilpie/servo,splav/servo,nnethercote/servo,g-k/servo,pyecs/servo,notriddle/servo,walac/servo,sadmansk/servo,paulrouget/servo,boghison/servo,kindersung/servo,brendandahl/servo,tempbottle/servo,nick-thompson/servo,zentner-kyle/servo,DominoTree/servo,upsuper/servo,GreenRecycleBin/servo,steveklabnik/servo,RenaudParis/servo,anthgur/servo,meh/servo,GyrosOfWar/servo,indykish/servo,bjwbell/servo,saneyuki/servo,meh/servo,saneyuki/servo,CJ8664/servo,samfoo/servo,saneyuki/servo,bjwbell/servo,indykish/servo,rentongzhang/servo,larsbergstrom/servo,bjwbell/servo,SimonSapin/servo,mattnenterprise/servo,DominoTree/servo,DominoTree/servo,aweinstock314/servo,dagnir/servo,runarberg/servo,aweinstock314/servo,ruud-v-a/servo,DominoTree/servo,ryancanhelpyou/servo,sadmansk/servo,echochamber/servo,wartman4404/servo,nnethercote/servo,bfrohs/servo,srbhklkrn/SERVOENGINE,hyowon/servo,nnethercote/servo,anthgur/servo,wartman4404/servo,Adenilson/prototype-viewing-distance,caldwell/servo,tschneidereit/servo,jimberlage/servo,huonw/servo,hyowon/servo,saneyuki/servo,vks/servo,fiji-flo/servo,deokjinkim/servo,aidanhs/servo,jimberlage/servo,srbhklkrn/SERVOENGINE,aweinstock314/servo,RenaudParis/servo,zentner-kyle/servo,jlegendary/servo,KiChjang/servo,dati91/servo,runarberg/servo,j3parker/servo,peterjoel/servo,huonw/servo,tempbottle/servo,KiChjang/servo,ConnorGBrewster/servo,mbrubeck/servo,szeged/servo,shrenikgala/servo,wpgallih/servo,meh/servo,steveklabnik/servo,evilpie/servo,rentongzhang/servo,tempbottle/servo,szeged/servo,Adenilson/prototype-viewing-distance,echochamber/servo,tafia/servo,GyrosOfWar/servo,A-deLuna/servo,tempbottle/servo,saratang/servo,nrc/servo,codemac/servo,deokjinkim/servo,eddyb/servo,j3parker/servo,canaltinova/servo,larsbergstrom/servo,brendandahl/servo,thiagopnts/servo,avadacatavra/servo,indykish/servo,nerith/servo,steveklabnik/servo,avadacatavra/servo,A-deLuna/servo,g-k/servo,saneyuki/servo,pyfisch/servo,karlito40/servo,paulrouget/servo,Shraddha512/servo,dagnir/servo,dagnir/servo,aweinstock314/servo,zentner-kyle/servo,rnestler/servo,dsandeephegde/servo,emilio/servo,tschneidereit/servo,youprofit/servo,mt2d2/servo,AnthonyBroadCrawford/servo,pyecs/servo,evilpie/servo,michaelwu/servo,wpgallih/servo,dati91/servo,ruud-v-a/servo,jdramani/servo,luniv/servo,rentongzhang/servo,A-deLuna/servo,rentongzhang/servo,nerith/servo,canaltinova/servo,nnethercote/servo,peterjoel/servo,szeged/servo,dagnir/servo,upsuper/servo,dagnir/servo,steveklabnik/servo,larsbergstrom/servo,ryancanhelpyou/servo,dsandeephegde/servo,michaelwu/servo,wpgallih/servo,mukilan/servo,mukilan/servo,mbrubeck/servo,snf/servo,snf/servo,nrc/servo,rixrix/servo,larsbergstrom/servo,brendandahl/servo,tempbottle/servo,ryancanhelpyou/servo,DominoTree/servo,aweinstock314/servo,froydnj/servo,akosel/servo,jimberlage/servo,pyfisch/servo,nrc/servo,brendandahl/servo,AnthonyBroadCrawford/servo,mt2d2/servo,pyfisch/servo,jgraham/servo,anthgur/servo,notriddle/servo,saratang/servo,sadmansk/servo,saratang/servo,emilio/servo,youprofit/servo,froydnj/servo,saneyuki/servo,saratang/servo,dmarcos/servo,zhangjunlei26/servo,dvberkel/servo,mbrubeck/servo,notriddle/servo,larsbergstrom/servo,deokjinkim/servo,paulrouget/servo,larsbergstrom/servo,s142857/servo,peterjoel/servo,upsuper/servo,ConnorGBrewster/servo,thiagopnts/servo,DominoTree/servo,nerith/servo,srbhklkrn/SERVOENGINE,fiji-flo/servo,youprofit/servo,mattnenterprise/servo,SimonSapin/servo,nrc/servo,AnthonyBroadCrawford/servo,snf/servo,karlito40/servo,upsuper/servo,peterjoel/servo,bjwbell/servo,dhananjay92/servo,tempbottle/servo,mukilan/servo,zentner-kyle/servo,mdibaiee/servo,peterjoel/servo,pgonda/servo,jimberlage/servo,meh/servo,pyecs/servo,samfoo/servo,codemac/servo,s142857/servo,nnethercote/servo,fiji-flo/servo,peterjoel/servo,s142857/servo,emilio/servo,WriterOfAlicrow/servo,RenaudParis/servo,SimonSapin/servo,ConnorGBrewster/servo,cbrewster/servo,Adenilson/prototype-viewing-distance,dvberkel/servo,notriddle/servo,jdramani/servo,KiChjang/servo,tafia/servo,paulrouget/servo,SimonSapin/servo,peterjoel/servo,caldwell/servo,nrc/servo,wpgallih/servo,tschneidereit/servo,szeged/servo,paulrouget/servo,boghison/servo,dati91/servo,emilio/servo,saneyuki/servo,codemac/servo,evilpie/servo,youprofit/servo,j3parker/servo,canaltinova/servo,notriddle/servo,A-deLuna/servo,huonw/servo,caldwell/servo,rixrix/servo,zentner-kyle/servo,huonw/servo,KiChjang/servo,pyfisch/servo,mdibaiee/servo,emilio/servo,CJ8664/servo,akosel/servo,szeged/servo,Shraddha512/servo,snf/servo,codemac/servo,saneyuki/servo,g-k/servo,tafia/servo,j3parker/servo,canaltinova/servo,shrenikgala/servo,bfrohs/servo,szeged/servo,s142857/servo,dhananjay92/servo,CJ8664/servo,nick-thompson/servo,brendandahl/servo,caldwell/servo,pyfisch/servo,rnestler/servo,AnthonyBroadCrawford/servo,codemac/servo,Shraddha512/servo,karlito40/servo,dhananjay92/servo,zhangjunlei26/servo,aidanhs/servo,luniv/servo,szeged/servo,splav/servo,ConnorGBrewster/servo,michaelwu/servo,luniv/servo,codemac/servo,AnthonyBroadCrawford/servo,huonw/servo,steveklabnik/servo,vks/servo,echochamber/servo,avadacatavra/servo,ryancanhelpyou/servo,notriddle/servo,zhangjunlei26/servo,anthgur/servo,youprofit/servo,kindersung/servo,walac/servo,brendandahl/servo,dsandeephegde/servo,snf/servo,steveklabnik/servo,ryancanhelpyou/servo,wartman4404/servo,s142857/servo,jimberlage/servo,avadacatavra/servo,shrenikgala/servo,avadacatavra/servo,rixrix/servo,boghison/servo,caldwell/servo,dati91/servo,aweinstock314/servo,zhangjunlei26/servo,hyowon/servo,GyrosOfWar/servo,caldwell/servo,cbrewster/servo,dsandeephegde/servo,snf/servo,WriterOfAlicrow/servo,s142857/servo,nerith/servo,fiji-flo/servo,KiChjang/servo,eddyb/servo,vks/servo,evilpie/servo,ruud-v-a/servo,rnestler/servo,froydnj/servo,chotchki/servo,pyecs/servo,dhananjay92/servo,akosel/servo,ConnorGBrewster/servo,walac/servo,canaltinova/servo,bfrohs/servo,karlito40/servo,mukilan/servo,akosel/servo,DominoTree/servo,larsbergstrom/servo,echochamber/servo,WriterOfAlicrow/servo,rixrix/servo,dsandeephegde/servo,peterjoel/servo,Adenilson/prototype-viewing-distance,pyecs/servo,froydnj/servo,nnethercote/servo,indykish/servo,CJ8664/servo,codemac/servo,mt2d2/servo,rnestler/servo,jgraham/servo,jlegendary/servo,eddyb/servo,aidanhs/servo,anthgur/servo,Shraddha512/servo,meh/servo,froydnj/servo,hyowon/servo,chotchki/servo,ruud-v-a/servo,eddyb/servo,GreenRecycleBin/servo,RenaudParis/servo,snf/servo,boghison/servo,SimonSapin/servo,karlito40/servo,jimberlage/servo,mbrubeck/servo,saratang/servo,wartman4404/servo,nick-thompson/servo,wpgallih/servo,evilpie/servo,dagnir/servo,notriddle/servo,avadacatavra/servo,j3parker/servo,huonw/servo,emilio/servo,karlito40/servo,srbhklkrn/SERVOENGINE,meh/servo,GreenRecycleBin/servo,fiji-flo/servo,jlegendary/servo,CJ8664/servo,pyecs/servo