Auto merge of #15245 - andreastt:webdriver-caps, r=jdm
Auto merge of #15245 - andreastt:webdriver-caps, r=jdm

Correct capabilities returned by WebDriver server

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These patches aligns Servo’s capabilities with those in the [WebDriver standard](https://w3c.github.io/webdriver/webdriver-spec.html). See each commit’s message for further information.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [x] These changes do not require tests because _Servo needs more work before it can pass WPT WebDriver tests_

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