fix data flash when panning, close #2082
fix data flash when panning, close #2082

Layers that get opacity should be HW-composited like supersurface,
otherwise it flickers when panning. Should in theory improve
performance as well.

mapmeld/iD,energiekollektiv/openmod.sh-id,tbicr/iD,digidem/iD,bagage/iD,edpop/iD,AndreasHae/iD,kepta/iD,andreic-telenav/iD,bagage/iD,tbicr/iD,AndreasHae/iD,1ec5/iD,bagage/iD,morray/iD,kartta-labs/iD,ngageoint/hootenanny-ui,ngageoint/hootenanny-ui,kepta/iD,zbycz/iD,zbycz/iD,morray/iD,mapmeld/iD,edpop/iD,energiekollektiv/openmod.sh-id,openstreetmap/iD,1ec5/iD,kartta-labs/iD,kartta-labs/iD,ngageoint/hootenanny-ui,edpop/iD,digidem/iD,mapmeld/iD,AndreasHae/iD,openstreetmap/iD,andreic-telenav/iD,openstreetmap/iD,1ec5/iD