Refactor the HarfBuzz shaper to be in line with modern Rust style
Refactor the HarfBuzz shaper to be in line with modern Rust style

bhearsum-bors/servo,youprofit/servo,pgonda/servo,mattnenterprise/servo,evilpie/servo,WriterOfAlicrow/servo,SimonSapin/servo,notriddle/servo,notriddle/servo,DominoTree/servo,srbhklkrn/SERVOENGINE,peterjoel/servo,notriddle/servo,caldwell/servo,mdibaiee/servo,vks/servo,fiji-flo/servo,canaltinova/servo,anthgur/servo,pcwalton/servo,g-k/servo,dagnir/servo,Shraddha512/servo,mbrubeck/servo,wpgallih/servo,saratang/servo,paulrouget/servo,bhearsum-bors/servo,rnestler/servo,huonw/servo,peterjoel/servo,steveklabnik/servo,snf/servo,tafia/servo,GreenRecycleBin/servo,kindersung/servo,shrenikgala/servo,pyfisch/servo,bfrohs/servo,ConnorGBrewster/servo,saneyuki/servo,DominoTree/servo,seanmonstar/servo,mdibaiee/servo,nerith/servo,rnestler/servo,SimonSapin/servo,jgraham/servo,dvberkel/servo,indykish/servo,tafia/servo,walac/servo,ConnorGBrewster/servo,dvberkel/servo,Shraddha512/servo,saneyuki/servo,mt2d2/servo,pyfisch/servo,A-deLuna/servo,tschneidereit/servo,caldwell/servo,snf/servo,vks/servo,rnestler/servo,KiChjang/servo,upsuper/servo,fiji-flo/servo,saneyuki/servo,zhangjunlei26/servo,aidanhs/servo,nrc/servo,DominoTree/servo,KiChjang/servo,youprofit/servo,snf/servo,wartman4404/servo,notriddle/servo,avadacatavra/servo,deokjinkim/servo,RenaudParis/servo,splav/servo,boghison/servo,larsbergstrom/servo,metajack/servo,pyfisch/servo,nick-thompson/servo,g-k/servo,CJ8664/servo,KiChjang/servo,meh/servo,sadmansk/servo,paulrouget/servo,aweinstock314/servo,anthgur/servo,samfoo/servo,chotchki/servo,GyrosOfWar/servo,karlito40/servo,luniv/servo,avadacatavra/servo,AnthonyBroadCrawford/servo,upsuper/servo,jlegendary/servo,jgraham/servo,vks/servo,nerith/servo,Shraddha512/servo,szeged/servo,peterjoel/servo,avadacatavra/servo,DominoTree/servo,zentner-kyle/servo,snf/servo,metajack/servo,steveklabnik/servo,indykish/servo,saratang/servo,tempbottle/servo,samfoo/servo,shrenikgala/servo,codemac/servo,ConnorGBrewster/servo,rnestler/servo,SimonSapin/servo,larsbergstrom/servo,emilio/servo,s142857/servo,KiChjang/servo,froydnj/servo,pyfisch/servo,juzer10/servo,mbrubeck/servo,wartman4404/servo,nnethercote/servo,wpgallih/servo,KiChjang/servo,hyowon/servo,anthgur/servo,paulrouget/servo,youprofit/servo,dati91/servo,michaelwu/servo,rixrix/servo,notriddle/servo,DominoTree/servo,saneyuki/servo,aidanhs/servo,ruud-v-a/servo,rentongzhang/servo,chotchki/servo,eddyb/servo,dati91/servo,nerith/servo,anthgur/servo,chotchki/servo,rixrix/servo,brendandahl/servo,cbrewster/servo,hyowon/servo,fiji-flo/servo,dhananjay92/servo,g-k/servo,pcwalton/servo,nnethercote/servo,jdramani/servo,wartman4404/servo,saneyuki/servo,tafia/servo,hyowon/servo,ConnorGBrewster/servo,akosel/servo,pcwalton/servo,peterjoel/servo,larsbergstrom/servo,upsuper/servo,anthgur/servo,boghison/servo,Aalhad/CanvasRenderingContext2DMozilla,nrc/servo,saratang/servo,canaltinova/servo,eddyb/servo,vks/servo,shrenikgala/servo,cbrewster/servo,mattnenterprise/servo,boghison/servo,walac/servo,luniv/servo,deokjinkim/servo,ConnorGBrewster/servo,caldwell/servo,owaspjocur/servo,fiji-flo/servo,nrc/servo,wpgallih/servo,samfoo/servo,rnestler/servo,ryancanhelpyou/servo,GreenRecycleBin/servo,eddyb/servo,dvberkel/servo,dvberkel/servo,peterjoel/servo,DominoTree/servo,rixrix/servo,evilpie/servo,owaspjocur/servo,dati91/servo,zhangjunlei26/servo,deokjinkim/servo,canaltinova/servo,jgraham/servo,larsbergstrom/servo,echochamber/servo,pyfisch/servo,brson/servo,codemac/servo,jgraham/servo,mukilan/servo,bjwbell/servo,canaltinova/servo,codemac/servo,mrobinson/servo,ruud-v-a/servo,akosel/servo,mbrubeck/servo,splav/servo,dhananjay92/servo,nrc/servo,canaltinova/servo,jlegendary/servo,mbrubeck/servo,zhangjunlei26/servo,jimberlage/servo,Aalhad/CanvasRenderingContext2DMozilla,caldwell/servo,szeged/servo,indykish/servo,paulrouget/servo,GyrosOfWar/servo,DominoTree/servo,avadacatavra/servo,j3parker/servo,dsandeephegde/servo,brson/servo,nnethercote/servo,nrc/servo,mdibaiee/servo,fiji-flo/servo,paulrouget/servo,pyecs/servo,dagnir/servo,steveklabnik/servo,owaspjocur/servo,zhangjunlei26/servo,aidanhs/servo,mt2d2/servo,bhearsum-bors/servo,ryancanhelpyou/servo,dsandeephegde/servo,zentner-kyle/servo,tempbottle/servo,cbrewster/servo,Aalhad/CanvasRenderingContext2DMozilla,steveklabnik/servo,echochamber/servo,nick-thompson/servo,SimonSapin/servo,dagnir/servo,aweinstock314/servo,nrc/servo,CJ8664/servo,A-deLuna/servo,GyrosOfWar/servo,GreenRecycleBin/servo,RenaudParis/servo,rixrix/servo,pyfisch/servo,fiji-flo/servo,indykish/servo,canaltinova/servo,jimberlage/servo,ryancanhelpyou/servo,jlegendary/servo,rentongzhang/servo,nerith/servo,ryancanhelpyou/servo,paulrouget/servo,GreenRecycleBin/servo,codemac/servo,bfrohs/servo,saneyuki/servo,notriddle/servo,karlito40/servo,evilpie/servo,nerith/servo,kindersung/servo,SimonSapin/servo,g-k/servo,kindersung/servo,ruud-v-a/servo,anthgur/servo,j3parker/servo,AnthonyBroadCrawford/servo,kindersung/servo,shrenikgala/servo,mattnenterprise/servo,tafia/servo,srbhklkrn/SERVOENGINE,ryancanhelpyou/servo,mrobinson/servo,cbrewster/servo,wala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ford/servo,jdramani/servo,snf/servo,caldwell/servo,dagnir/servo,rentongzhang/servo,A-deLuna/servo,dvberkel/servo,karlito40/servo,hyowon/servo,bfrohs/servo,zhangjunlei26/servo,fiji-flo/servo,nick-thompson/servo,CJ8664/servo,vks/servo,karlito40/servo,pyecs/servo,bjwbell/servo,DominoTree/servo,GreenRecycleBin/servo,splav/servo,brendandahl/servo,j3parker/servo,eddyb/servo,akosel/servo,luniv/servo,tempbottle/servo,samfoo/servo,boghison/servo,saratang/servo,nick-thompson/servo,pyecs/servo,seanmonstar/servo,avadacatavra/servo,juzer10/servo,paulrouget/servo,nick-thompson/servo,AnthonyBroadCrawford/servo,j3parker/servo,pyecs/servo,SimonSapin/servo,KiChjang/servo,eddyb/servo,bjwbell/servo,KiChjang/servo,peterjoel/servo,shrenikgala/servo,WriterOfAlicrow/servo,mukilan/servo,rixrix/servo,aidanhs/servo,szeged/servo,notriddle/servo,mbrubeck/servo,nick-thompson/servo,seanmonstar/servo,aweinstock314/servo,mt2d2/servo,runarberg/servo,sadmansk/servo,rnestler/servo,jdramani/servo,metajack/servo,chotchki/servo,CJ8664/servo,pcwalton/servo,notriddle/servo,pyfisch/servo,WriterOfAlicrow/servo,jgraham/servo,tempbottle/servo,emilio/servo,snf/servo,pgonda/servo,echochamber/servo,runarberg/servo,avadacatavra/servo,brendandahl/servo,dhananjay92/servo,seanmonstar/servo,owaspjocur/servo,jlegendary/servo,steveklabnik/servo,huonw/servo,jgraham/servo,g-k/servo,thiagopnts/servo,GyrosOfWar/servo,pyfisch/servo,akosel/servo,meh/servo,froydnj/servo,emilio/servo,szeged/servo,pyfisch/servo,luniv/servo,ruud-v-a/servo,mbrubeck/servo,froydnj/servo,michaelwu/servo,dhananjay92/servo,peterjoel/servo,rnestler/servo,zentner-kyle/servo,pgonda/servo,zhangjunlei26/servo,dati91/servo,Aalhad/CanvasRenderingContext2DMozilla,wpgallih/servo,dsandeephegde/servo,jdramani/servo,bfrohs/servo,rixrix/servo,AnthonyBroadCrawford/servo,WriterOfAlicrow/servo,wartman4404/servo,mt2d2/servo,larsbergstrom/servo,froydnj/servo,jimberlage/servo,bjwbell/servo,juzer10/servo,froydnj/servo,brendandahl/servo,sadmansk/servo,Shraddha512/servo,luniv/servo,nerith/servo,cbrewster/servo,jimberlage/servo,wartman4404/servo,meh/servo,s142857/servo,bhearsum-bors/servo,cbrewster/servo,mbrubeck/servo,wartman4404/servo,notriddle/servo,echochamber/servo,zhangjunlei26/servo,s142857/servo,larsbergstrom/servo,michaelwu/servo,A-deLuna/servo,ruud-v-a/servo,Adenilson/prototype-viewing-distance,jlegendary/servo,dati91/servo,emilio/servo,karlito40/servo,srbhklkrn/SERVOENGINE,j3parker/servo,splav/servo,peterjoel/servo,huonw/servo,bjwbell/servo,shrenikgala/servo,dsandeephegde/servo,deokjinkim/servo,akosel/servo,nnethercote/servo,zentner-kyle/servo,zentner-kyle/servo,bjwbell/servo,boghison/servo,thiagopnts/servo,szeged/servo,AnthonyBroadCrawford/servo,juzer10/servo,aweinstock314/servo,pcwalton/servo,jdramani/servo,sadmansk/servo,nnethercote/servo,Adenilson/prototype-viewing-distance,aweinstock314/servo,hyowon/servo,rentongzhang/servo,pcwalton/servo,codemac/servo,tschneidereit/servo,larsbergstrom/servo,youprofit/servo,wpgallih/servo,anthgur/servo,echochamber/servo