Auto merge of #7669 - mbrubeck:zoom, r=glennw
Auto merge of #7669 - mbrubeck:zoom, r=glennw

Set default limits on page zoom and pinch zoom

Currently these both clamp to 100% in one direction and are unbounded in the other direction.  This sets default zoom constraints of 10% to 800%.  r? @glennw

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nnethercote/servo,nnethercote/servo,runarberg/servo,runarberg/servo,dati91/servo,mbrubeck/servo,brendandahl/servo,DominoTree/servo,DominoTree/servo,pyfisch/servo,fiji-flo/servo,thiagopnts/servo,ConnorGBrewster/servo,KiChjang/servo,bjwbell/servo,fiji-flo/servo,ConnorGBrewster/servo,nnethercote/servo,avadacatavra/servo,avadacatavra/servo,KiChjang/servo,rnestler/servo,paulrouget/servo,RenaudParis/servo,DominoTree/servo,j3parker/servo,anthgur/servo,notriddle/servo,fiji-flo/servo,sadmansk/servo,nnethercote/servo,szeged/servo,SimonSapin/servo,szeged/servo,paulrouget/servo,bjwbell/servo,paulrouget/servo,eddyb/servo,dsandeephegde/servo,splav/servo,mattnenterprise/servo,bjwbell/servo,splav/servo,eddyb/servo,mbrubeck/servo,jimberlage/servo,emilio/servo,szeged/servo,saneyuki/servo,peterjoel/servo,mattnenterprise/servo,paulrouget/servo,szeged/servo,peterjoel/servo,splav/servo,runarberg/servo,steveklabnik/servo,DominoTree/servo,thiagopnts/servo,cbrewster/servo,AnthonyBroadCrawford/servo,AnthonyBroadCrawford/servo,j3parker/servo,rnestler/servo,nrc/servo,bjwbell/servo,sadmansk/servo,RenaudParis/servo,bjwbell/servo,thiagopnts/servo,canaltinova/servo,ConnorGBrewster/servo,SimonSapin/servo,splav/servo,larsbergstrom/servo,thiagopnts/servo,nrc/servo,DominoTree/servo,cbrewster/servo,dati91/servo,upsuper/servo,notriddle/servo,SimonSapin/servo,eddyb/servo,j3parker/servo,avadacatavra/servo,fiji-flo/servo,anthgur/servo,mbrubeck/servo,saneyuki/servo,mattnenterprise/servo,pyfisch/servo,cbrewster/servo,dsandeephegde/servo,dagnir/servo,jimberlage/servo,saneyuki/servo,saneyuki/servo,SimonSapin/servo,upsuper/servo,jimberlage/servo,nrc/servo,cbrewster/servo,KiChjang/servo,dati91/servo,DominoTree/servo,dsandeephegde/servo,szeged/servo,KiChjang/servo,saneyuki/servo,RenaudParis/servo,dsandeephegde/servo,saneyuki/servo,dagnir/servo,notriddle/servo,brendandahl/servo,nnethercote/servo,upsuper/servo,mbrubeck/servo,eddyb/servo,mattnenterprise/servo,dsandeephegde/servo,sadmansk/servo,DominoTree/servo,AnthonyBroadCrawford/servo,mattnenterprise/servo,j3parker/servo,eddyb/servo,thiagopnts/servo,peterjoel/servo,brendandahl/servo,avadacatavra/servo,saneyuki/servo,steveklabnik/servo,DominoTree/servo,splav/servo,canaltinova/servo,CJ8664/servo,fiji-flo/servo,emilio/servo,ConnorGBrewster/servo,dsandeephegde/servo,dagnir/servo,cbrewster/servo,KiChjang/servo,emilio/servo,pyfisch/servo,SimonSapin/servo,nnethercote/servo,dagnir/servo,emilio/servo,anthgur/servo,DominoTree/servo,jimberlage/servo,peterjoel/servo,canaltinova/servo,RenaudParis/servo,sadmansk/servo,emilio/servo,mbrubeck/servo,AnthonyBroadCrawford/servo,mattnenterprise/servo,thiagopnts/servo,emilio/servo,upsuper/servo,cbrewster/servo,dati91/servo,saneyuki/servo,steveklabnik/servo,rnestler/servo,steveklabnik/servo,szeged/servo,splav/servo,upsuper/servo,thiagopnts/servo,szeged/servo,sadmansk/servo,splav/servo,szeged/servo,CJ8664/servo,KiChjang/servo,saneyuki/servo,CJ8664/servo,eddyb/servo,upsuper/servo,anthgur/servo,rnestler/servo,j3parker/servo,CJ8664/servo,nnethercote/servo,brendandahl/servo,peterjoel/servo,KiChjang/servo,pyfisch/servo,sadmansk/servo,mbrubeck/servo,KiChjang/servo,steveklabnik/servo,fiji-flo/servo,mattnenterprise/servo,avadacatavra/servo,peterjoel/servo,larsbergstrom/servo,nnethercote/servo,CJ8664/servo,thiagopnts/servo,jimberlage/servo,dsandeephegde/servo,rnestler/servo,larsbergstrom/servo,dagnir/servo,notriddle/servo,larsbergstrom/servo,brendandahl/servo,ConnorGBrewster/servo,canaltinova/servo,j3parker/servo,ConnorGBrewster/servo,AnthonyBroadCrawford/servo,brendandahl/servo,larsbergstrom/servo,cbrewster/servo,pyfisch/servo,dati91/servo,paulrouget/servo,splav/servo,ConnorGBrewster/servo,nnethercote/servo,paulrouget/servo,rnestler/servo,canaltinova/servo,KiChjang/servo,AnthonyBroadCrawford/servo,szeged/servo,steveklabnik/servo,mattnenterprise/servo,jimberlage/servo,canaltinova/servo,jimberlage/servo,paulrouget/servo,szeged/servo,brendandahl/servo,emilio/servo,notriddle/servo,RenaudParis/servo,emilio/servo,jimberlage/servo,runarberg/servo,peterjoel/servo,CJ8664/servo,larsbergstrom/servo,mbrubeck/servo,peterjoel/servo,dati91/servo,saneyuki/servo,dagnir/servo,anthgur/servo,rnestler/servo,canaltinova/servo,splav/servo,dati91/servo,eddyb/servo,upsuper/servo,bjwbell/servo,KiChjang/servo,steveklabnik/servo,DominoTree/servo,avadacatavra/servo,dagnir/servo,avadacatavra/servo,runarberg/servo,runarberg/servo,eddyb/servo,nnethercote/servo,paulrouget/servo,larsbergstrom/servo,emilio/servo,jimberlage/servo,notriddle/servo,fiji-flo/servo,larsbergstrom/servo,sadmansk/servo,dati91/servo,rnestler/servo,larsbergstrom/servo,larsbergstrom/servo,runarberg/servo,SimonSapin/servo,pyfisch/servo,cbrewster/servo,SimonSapin/servo,nrc/servo,ConnorGBrewster/servo,anthgur/servo,pyfisch/servo,SimonSapin/servo,pyfisch/servo,paulrouget/servo,canaltinova/servo,notriddle/servo,j3parker/servo,paulrouget/servo,pyfisch/servo,notriddle/servo,CJ8664/servo,bjwbell/servo,notriddle/servo,nrc/servo,RenaudParis/servo,RenaudParis/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