style: Fix grid line serialization to avoid redundant spacing.
style: Fix grid line serialization to avoid redundant spacing.

This fixes https://bugzilla.mozilla.org/show_bug.cgi?id=1425227.

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