Handle BORDER_STYLE_MASK.
Handle BORDER_STYLE_MASK.

Gecko uses the higher bits of certain border-style-like properties to store other things.
This duplicates the logic in Gecko's {Get,Set}BorderStyle and similar.

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