Auto merge of #13093 - ashrko619:cache-element-classnames, r=nox
Auto merge of #13093 - ashrko619:cache-element-classnames, r=nox

Remove unneeded clone in the style system cache

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- [X] These changes fix #13089  (github issue number if applicable).

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