Auto merge of #19039 - sylvestre:master, r=emilio
Auto merge of #19039 - sylvestre:master, r=emilio

Support multi lines declarations in the parsing of the Fx header files

For example, in dom/base/nsGkAtomList.h, we currently have:

`GK_ATOM(mouseWheel, "mouseWheel")  // For discrete wheel events (e.g. not OSX magic mouse)`

but if we change to
```
GK_ATOM(mouseWheel,
        "mouseWheel")  // For discrete wheel events (e.g. not OSX magic mouse)
```
The parser didn't handle the declaration

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