Auto merge of #17691 - emilio:nondeter, r=Manishearth
Auto merge of #17691 - emilio:nondeter, r=Manishearth

stylo: Fix causes of non-determinism in gecko_properties.rs.

We should sort out all the different ways we have to get sides and all those
nasty loops, eventually...

Bug: 1380327
Reviewed-By: Manishearth
MozReview-Commit-ID: 4lAPEGeZaik

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/17691)
<!-- Reviewable:end -->

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