Auto merge of #7729 - Ms2ger:reftest-gates, r=jdm
Auto merge of #7729 - Ms2ger:reftest-gates, r=jdm

Remove the now-stable append and result_expect feature gates from reftest.



<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/7729)
<!-- Reviewable:end -->

avadacatavra/servo,sadmansk/servo,rnestler/servo,cbrewster/servo,rnestler/servo,canaltinova/servo,DominoTree/servo,larsbergstrom/servo,sadmansk/servo,peterjoel/servo,paulrouget/servo,nrc/servo,jimberlage/servo,steveklabnik/servo,KiChjang/servo,thiagopnts/servo,canaltinova/servo,szeged/servo,saneyuki/servo,anthgur/servo,runarberg/servo,anthgur/servo,saneyuki/servo,runarberg/servo,cbrewster/servo,nnethercote/servo,rnestler/servo,eddyb/servo,nnethercote/servo,larsbergstrom/servo,emilio/servo,pyfisch/servo,KiChjang/servo,runarberg/servo,nrc/servo,larsbergstrom/servo,SimonSapin/servo,splav/servo,CJ8664/servo,upsuper/servo,paulrouget/servo,CJ8664/servo,mbrubeck/servo,CJ8664/servo,splav/servo,paulrouget/servo,rnestler/servo,ConnorGBrewster/servo,anthgur/servo,canaltinova/servo,DominoTree/servo,szeged/servo,paulrouget/servo,steveklabnik/servo,anthgur/servo,mattnenterprise/servo,thiagopnts/servo,runarberg/servo,j3parker/servo,nnethercote/servo,splav/servo,ConnorGBrewster/servo,dsandeephegde/servo,nrc/servo,pyfisch/servo,splav/servo,saneyuki/servo,canaltinova/servo,splav/servo,upsuper/servo,RenaudParis/servo,notriddle/servo,j3parker/servo,canaltinova/servo,sadmansk/servo,sadmansk/servo,nrc/servo,SimonSapin/servo,jimberlage/servo,peterjoel/servo,szeged/servo,cbrewster/servo,steveklabnik/servo,dati91/servo,notriddle/servo,SimonSapin/servo,SimonSapin/servo,rnestler/servo,RenaudParis/servo,larsbergstrom/servo,mbrubeck/servo,pyfisch/servo,nnethercote/servo,mattnenterprise/servo,eddyb/servo,KiChjang/servo,nnethercote/servo,mattnenterprise/servo,szeged/servo,RenaudParis/servo,cbrewster/servo,CJ8664/servo,emilio/servo,ConnorGBrewster/servo,jimberlage/servo,thiagopnts/servo,DominoTree/servo,DominoTree/servo,anthgur/servo,eddyb/servo,runarberg/servo,pyfisch/servo,anthgur/servo,saneyuki/servo,dati91/servo,rnestler/servo,paulrouget/servo,notriddle/servo,dati91/servo,emilio/servo,sadmansk/servo,saneyuki/servo,mbrubeck/servo,DominoTree/servo,DominoTree/servo,szeged/servo,pyfisch/servo,fiji-flo/servo,notriddle/servo,KiChjang/servo,anthgur/servo,eddyb/servo,fiji-flo/servo,emilio/servo,fiji-flo/servo,sadmansk/servo,mattnenterprise/servo,dsandeephegde/servo,upsuper/servo,fiji-flo/servo,jimberlage/servo,KiChjang/servo,mbrubeck/servo,DominoTree/servo,peterjoel/servo,avadacatavra/servo,dati91/servo,CJ8664/servo,SimonSapin/servo,SimonSapin/servo,nnethercote/servo,emilio/servo,mbrubeck/servo,dsandeephegde/servo,canaltinova/servo,j3parker/servo,saneyuki/servo,RenaudParis/servo,jimberlage/servo,splav/servo,CJ8664/servo,thiagopnts/servo,szeged/servo,dati91/servo,cbrewster/servo,upsuper/servo,larsbergstrom/servo,szeged/servo,KiChjang/servo,nnethercote/servo,peterjoel/servo,runarberg/servo,mbrubeck/servo,pyfisch/servo,sadmansk/servo,larsbergstrom/servo,mattnenterprise/servo,KiChjang/servo,mbrubeck/servo,notriddle/servo,thiagopnts/servo,emilio/servo,eddyb/servo,notriddle/servo,szeged/servo,pyfisch/servo,steveklabnik/servo,steveklabnik/servo,dsandeephegde/servo,saneyuki/servo,ConnorGBrewster/servo,avadacatavra/servo,peterjoel/servo,SimonSapin/servo,notriddle/servo,splav/servo,pyfisch/servo,szeged/servo,paulrouget/servo,dsandeephegde/servo,ConnorGBrewster/servo,ConnorGBrewster/servo,paulrouget/servo,nnethercote/servo,fiji-flo/servo,paulrouget/servo,j3parker/servo,emilio/servo,thiagopnts/servo,splav/servo,dati91/servo,avadacatavra/servo,runarberg/servo,jimberlage/servo,saneyuki/servo,saneyuki/servo,peterjoel/servo,nrc/servo,jimberlage/servo,cbrewster/servo,avadacatavra/servo,SimonSapin/servo,eddyb/servo,eddyb/servo,sadmansk/servo,CJ8664/servo,DominoTree/servo,emilio/servo,saneyuki/servo,peterjoel/servo,KiChjang/servo,j3parker/servo,splav/servo,mattnenterprise/servo,nnethercote/servo,larsbergstrom/servo,cbrewster/servo,RenaudParis/servo,notriddle/servo,RenaudParis/servo,mbrubeck/servo,splav/servo,fiji-flo/servo,jimberlage/servo,fiji-flo/servo,fiji-flo/servo,canaltinova/servo,emilio/servo,rnestler/servo,peterjoel/servo,larsbergstrom/servo,j3parker/servo,emilio/servo,eddyb/servo,avadacatavra/servo,DominoTree/servo,ConnorGBrewster/servo,larsbergstrom/servo,KiChjang/servo,steveklabnik/servo,jimberlage/servo,thiagopnts/servo,avadacatavra/servo,CJ8664/servo,dati91/servo,ConnorGBrewster/servo,upsuper/servo,nrc/servo,KiChjang/servo,paulrouget/servo,dsandeephegde/servo,szeged/servo,RenaudParis/servo,anthgur/servo,dati91/servo,dsandeephegde/servo,nrc/servo,steveklabnik/servo,j3parker/servo,nnethercote/servo,thiagopnts/servo,upsuper/servo,dsandeephegde/servo,peterjoel/servo,cbrewster/servo,pyfisch/servo,upsuper/servo,DominoTree/servo,notriddle/servo,peterjoel/servo,pyfisch/servo,notriddle/servo,upsuper/servo,mattnenterprise/servo,canaltinova/servo,rnestler/servo,avadacatavra/servo,larsbergstrom/servo,paulrouget/servo,mattnenterprise/servo