Auto merge of #9701 - Ms2ger:listener-is-some, r=KiChjang
Auto merge of #9701 - Ms2ger:listener-is-some, r=KiChjang

Use if-let in set_inline_event_listener.

<!-- Reviewable:start -->
[<img src="https://reviewable.io/review_button.svg" height="40" alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/servo/9701)
<!-- Reviewable:end -->

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