guard against null tileInfo
Merge pull request #832 from perrygeo/2.12-perrygeo

guard against null tileInfo
No .olTileReplacing class for singleTile layers

This fixes a regression for singleTile layers with transitionEffect set to
'resize', where the .olTileReplacing class was not removed from the tile.
After #829 fallThrough needs to be true for this test
Merge pull request #836 from ahocevar/replacing

No .olTileReplacing class for singleTile layers. r=@bartvde
Process queue immediately when params change

This fixes an issue where the queue would never be processed when a layer
is updated using mergeNewParams.
Merge pull request #839 from ahocevar/tilemanager-changelayer

Process queue immediately when params change. r=@bartvde
Merge branch 'master' of github.com:openlayers/openlayers into dimNG