Servo changes for updated Gecko theme constants in bug 1367577.
Servo changes for updated Gecko theme constants in bug 1367577.

This is a little bit odd, because I didn't want to do all the work to
convert the theme constants to an enum class (although that would be
nice to do in the future).  So this makes them a regular enum, but still
uses gecko_constant_prefix rather than gecko_enum_prefix because that
makes it possible to add the NS_THEME_ prefix that's still present.

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