auto merge of #5245 : nnethercote/servo/only-one-quit-event, r=glennw
auto merge of #5245 : nnethercote/servo/only-one-quit-event, r=glennw

This fixes #5234, in that the huge memory spike disappears. It still takes ~15 seconds for the window to actually disappear after that first `Quit` event is received by the IOCompositor. Maybe that's a pre-existing problem.

There may be better ways to do this, like handling it on the sending side (i.e. within glutin) instead of the receiving side. I just did it this way because it seemed like the easiest thing.

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