Remove an invalid assertion in fire_timer.
Remove an invalid assertion in fire_timer.

It's not clear to me if this is something we should expect to happen, but it
does indeed happen, so we should disable the assertion while we investigate.

Fixes #9984.

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