Tweak CalcLengthOrPercentage to use pixel value.
Tweak CalcLengthOrPercentage to use pixel value.

We compute the distance for eCSSUnit_Calc by pixel value in Gecko,
so let's follow the same rules.

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