Remove unnecessary `mut` on variables declared in ports/gonk/src/window.rs
Remove unnecessary `mut` on variables declared in ports/gonk/src/window.rs

Fixes #7048.

brendandahl/servo,canaltinova/servo,jimberlage/servo,tafia/servo,saneyuki/servo,eddyb/servo,runarberg/servo,thiagopnts/servo,peterjoel/servo,wartman4404/servo,zentner-kyle/servo,bjwbell/servo,KiChjang/servo,jlegendary/servo,saratang/servo,boghison/servo,vks/servo,dati91/servo,kindersung/servo,rnestler/servo,RenaudParis/servo,tempbottle/servo,sadmansk/servo,GyrosOfWar/servo,walac/servo,tafia/servo,steveklabnik/servo,dagnir/servo,anthgur/servo,boghison/servo,saneyuki/servo,jdramani/servo,huonw/servo,rnestler/servo,szeged/servo,jimberlage/servo,j3parker/servo,splav/servo,thiagopnts/servo,larsbergstrom/servo,splav/servo,dsandeephegde/servo,rnestler/servo,brendandahl/servo,thiagopnts/servo,eddyb/servo,KiChjang/servo,paulrouget/servo,youprofit/servo,CJ8664/servo,huonw/servo,CJ8664/servo,youprofit/servo,jdramani/servo,nnethercote/servo,mattnenterprise/servo,A-deLuna/servo,mattnenterprise/servo,pyfisch/servo,notriddle/servo,huonw/servo,nrc/servo,canaltinova/servo,paulrouget/servo,g-k/servo,j3parker/servo,jimberlage/servo,wartman4404/servo,runarberg/servo,pyfisch/servo,emilio/servo,walac/servo,rentongzhang/servo,meh/servo,ConnorGBrewster/servo,A-deLuna/servo,jdramani/servo,aidanhs/servo,mdibaiee/servo,akosel/servo,youprofit/servo,dati91/servo,DominoTree/servo,GyrosOfWar/servo,emilio/servo,avadacatavra/servo,notriddle/servo,dhananjay92/servo,AnthonyBroadCrawford/servo,jlegendary/servo,huonw/servo,walac/servo,RenaudParis/servo,thiagopnts/servo,walac/servo,KiChjang/servo,caldwell/servo,g-k/servo,dhananjay92/servo,akosel/servo,larsbergstrom/servo,peterjoel/servo,szeged/servo,KiChjang/servo,dsandeephegde/servo,cbrewster/servo,dsandeephegde/servo,wartman4404/servo,walac/servo,upsuper/servo,aidanhs/servo,youprofit/servo,notriddle/servo,CJ8664/servo,splav/servo,tafia/servo,nnethercote/servo,dati91/servo,youprofit/servo,larsbergstrom/servo,nrc/servo,fiji-flo/servo,tafia/servo,kindersung/servo,emilio/servo,meh/servo,avadacatavra/servo,jlegendary/servo,jdramani/servo,fiji-flo/servo,pyfisch/servo,cbrewster/servo,aidanhs/servo,g-k/servo,saratang/servo,nrc/servo,kindersung/servo,SimonSapin/servo,akosel/servo,rentongzhang/servo,anthgur/servo,caldwell/servo,caldwell/servo,dagnir/servo,jimberlage/servo,tempbottle/servo,bjwbell/servo,saneyuki/servo,ConnorGBrewster/servo,boghison/servo,brendandahl/servo,thiagopnts/servo,mattnenterprise/servo,upsuper/servo,mattnenterprise/servo,zentner-kyle/servo,saratang/servo,fiji-flo/servo,eddyb/servo,paulrouget/servo,saratang/servo,larsbergstrom/servo,peterjoel/servo,jlegendary/servo,kindersung/servo,avadacatavra/servo,meh/servo,paulrouget/servo,rentongzhang/servo,bjwbell/servo,tafia/servo,ConnorGBrewster/servo,A-deLuna/servo,paulrouget/servo,CJ8664/servo,dati91/servo,peterjoel/servo,DominoTree/servo,jdramani/servo,GyrosOfWar/servo,youprofit/servo,splav/servo,dvberkel/servo,dvberkel/servo,szeged/servo,nnethercote/servo,rentongzhang/servo,nrc/servo,pyfisch/servo,dhananjay92/servo,AnthonyBroadCrawford/servo,steveklabnik/servo,GyrosOfWar/servo,A-deLuna/servo,mbrubeck/servo,eddyb/servo,caldwell/servo,paulrouget/servo,nnethercote/servo,szeged/servo,splav/servo,rnestler/servo,runarberg/servo,emilio/servo,dvberkel/servo,walac/servo,GyrosOfWar/servo,mdibaiee/servo,j3parker/servo,dati91/servo,vks/servo,kindersung/servo,zentner-kyle/servo,canaltinova/servo,nrc/servo,steveklabnik/servo,szeged/servo,j3parker/servo,emilio/servo,vks/servo,nnethercote/servo,brendandahl/servo,paulrouget/servo,KiChjang/servo,akosel/servo,mdibaiee/servo,avadacatavra/servo,runarberg/servo,WriterOfAlicrow/servo,codemac/servo,paulrouget/servo,notriddle/servo,WriterOfAlicrow/servo,CJ8664/servo,g-k/servo,mdibaiee/servo,bjwbell/servo,DominoTree/servo,eddyb/servo,rentongzhang/servo,SimonSapin/servo,j3parker/servo,g-k/servo,paulrouget/servo,DominoTree/servo,tempbottle/servo,cbrewster/servo,dagnir/servo,nnethercote/servo,dati91/servo,j3parker/servo,RenaudParis/servo,g-k/servo,sadmansk/servo,dvberkel/servo,rnestler/servo,anthgur/servo,nnethercote/servo,pyfisch/servo,splav/servo,jlegendary/servo,canaltinova/servo,aidanhs/servo,sadmansk/servo,A-deLuna/servo,dagnir/servo,peterjoel/servo,akosel/servo,codemac/servo,vks/servo,mbrubeck/servo,dati91/servo,notriddle/servo,jimberlage/servo,upsuper/servo,codemac/servo,runarberg/servo,codemac/servo,dsandeephegde/servo,upsuper/servo,mbrubeck/servo,SimonSapin/servo,bjwbell/servo,walac/servo,szeged/servo,mdibaiee/servo,vks/servo,ConnorGBrewster/servo,dhananjay92/servo,caldwell/servo,tempbottle/servo,larsbergstrom/servo,dvberkel/servo,thiagopnts/servo,emilio/servo,caldwell/servo,szeged/servo,mbrubeck/servo,aidanhs/servo,SimonSapin/servo,KiChjang/servo,AnthonyBroadCrawford/servo,notriddle/servo,peterjoel/servo,akosel/servo,canaltinova/servo,dvberkel/servo,WriterOfAlicrow/servo,kindersung/servo,SimonSapin/servo,upsuper/servo,anthgur/servo,ConnorGBrewster/servo,bjwbell/servo,pyfisch/servo,fiji-flo/servo,DominoTree/servo,RenaudParis/servo,jimberlage/servo,thiagopnts/servo,CJ8664/servo,A-deLuna/servo,dsandeephegde/servo,ConnorGBrewster/servo,zentner-kyle/servo,saneyuki/servo,aidanhs/servo,jimberlage/servo,boghison/servo,nnethercote/servo,peterjoel/servo,avadacatavra/servo,huonw/servo,pyfisch/servo,emilio/servo,saratang/servo,emilio/servo,dsandeephegde/servo,sadmansk/servo,dhananjay92/servo,rentongzhang/servo,peterjoel/servo,ConnorGBrewster/servo,mattnenterprise/servo,mdibaiee/servo,KiChjang/servo,avadacatavra/servo,meh/servo,huonw/servo,eddyb/servo,CJ8664/servo,saneyuki/servo,tafia/servo,brendandahl/servo,KiChjang/servo,szeged/servo,dhananjay92/servo,cbrewster/servo,eddyb/servo,anthgur/servo,mattnenterprise/servo,splav/servo,CJ8664/servo,RenaudParis/servo,vks/servo,g-k/servo,runarberg/servo,saneyuki/servo,mbrubeck/servo,brendandahl/servo,saneyuki/servo,steveklabnik/servo,meh/servo,cbrewster/servo,dagnir/servo,KiChjang/servo,szeged/servo,GyrosOfWar/servo,jimberlage/servo,KiChjang/servo,paulrouget/servo,nnethercote/servo,j3parker/servo,notriddle/servo,peterjoel/servo,splav/servo,jdramani/servo,saneyuki/servo,steveklabnik/servo,meh/servo,AnthonyBroadCrawford/servo,wartman4404/servo,codemac/servo,AnthonyBroadCrawford/servo,dsandeephegde/servo,upsuper/servo,runarberg/servo,rnestler/servo,anthgur/servo,canaltinova/servo,AnthonyBroadCrawford/servo,jimberlage/servo,avadacatavra/servo,SimonSapin/servo,upsuper/servo,DominoTree/servo,larsbergstrom/servo,DominoTree/servo,codemac/servo,dsandeephegde/servo,A-deLuna/servo,anthgur/servo,fiji-flo/servo,DominoTree/servo,canaltinova/servo,szeged/servo,avadacatavra/servo,mattnenterprise/servo,jdramani/servo,dagnir/servo,upsuper/servo,wartman4404/servo,AnthonyBroadCrawford/servo,vks/servo,WriterOfAlicrow/servo,kindersung/servo,notriddle/servo,saratang/servo,DominoTree/servo,akosel/servo,pyfisch/servo,youprofit/servo,saneyuki/servo,aidanhs/servo,rnestler/servo,nrc/servo,rentongzhang/servo,steveklabnik/servo,jlegendary/servo,bjwbell/servo,boghison/servo,WriterOfAlicrow/servo,fiji-flo/servo,steveklabnik/servo,fiji-flo/servo,fiji-flo/servo,cbrewster/servo,larsbergstrom/servo,sadmansk/servo,nnethercote/servo,splav/servo,RenaudParis/servo,boghison/servo,wartman4404/servo,RenaudParis/servo,mdibaiee/servo,pyfisch/servo,zentner-kyle/servo,WriterOfAlicrow/servo,zentner-kyle/servo,sadmansk/servo,dati91/servo,saratang/servo,dagnir/servo,canaltinova/servo,larsbergstrom/servo,jlegendary/servo,notriddle/servo,boghison/servo,larsbergstrom/servo,emilio/servo,tafia/servo,dvberkel/servo,WriterOfAlicrow/servo,pyfisch/servo,meh/servo,brendandahl/servo,peterjoel/servo,tempbottle/servo,sadmansk/servo,cbrewster/servo,thiagopnts/servo,cbrewster/servo,emilio/servo,mbrubeck/servo,saneyuki/servo,mbrubeck/servo,zentner-kyle/servo,ConnorGBrewster/servo,caldwell/servo,codemac/servo,sadmansk/servo,GyrosOfWar/servo,notriddle/servo,SimonSapin/servo,rnestler/servo,eddyb/servo,DominoTree/servo,tempbottle/servo,mbrubeck/servo,dhananjay92/servo,wartman4404/servo,nrc/servo,mattnenterprise/servo,larsbergstrom/servo,huonw/servo,splav/servo,tempbottle/servo,SimonSapin/servo,anthgur/servo