Auto merge of #19528 - asajeffrey:test-perf-measure-loadEventEnd, r=avadacatavra
Auto merge of #19528 - asajeffrey:test-perf-measure-loadEventEnd, r=avadacatavra

Capture loadEventEnd in test-perf

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Capture perf-test data after the load event has finished firing.

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- [X] These changes do not require tests because this is test infrastructure

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