Fix a build warning in animation.rs.
Fix a build warning in animation.rs.

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