Auto merge of #10299 - mbrubeck:selection-style, r=jdm
Auto merge of #10299 - mbrubeck:selection-style, r=jdm

Set a default ::selection style

Since we no longer have a hard-coded default after #10252.

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