stylo: Fix a serialization bug for string pseudos.
stylo: Fix a serialization bug for string pseudos.

The string is null-terminated, so we need to avoid passing that last null
character.

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