Use opt_this instead of opt_scope in ol.Observable
Use opt_this instead of opt_obj in ol.Collection
Use opt_this instead of opt_obj in ol.Map
Use opt_this instead of opt_obj in ol.renderer.Layer
Use opt_this instead of opt_obj in ol.source.Vector
Use opt_this instead of opt_obj in ol.structs.Buffer
Use opt_this instead of opt_obj in ol.structs.IntegerSet
Use opt_this instead of opt_obj in ol.structs.LRUCache
Use opt_this instead of opt_obj in ol.structs.RBush
Use opt_this instead of opt_obj in ol.tilegrid.TileGrid
Use opt_this instead of opt_obj in ol.xml
Remove ol.format.Format#readFeaturesAsync
Merge pull request #1538 from twpayne/vector-api-this

[vector-api] Use opt_this for this arguments
Merge pull request #1537 from twpayne/vector-api-remove-read-features-async

[vector-api] Remove ol.format.Format#readFeaturesAsync
Add pixelRatio to ol.TileUrlFunction
Add pixelRatio to ol.source.Tile#getTile
Add ol.source.Tile#getTileGridForProjection
Use ol.source.Tile#getTileGridForProjection
Add ol.source.Tile#getTilePixelSize
Add HiDPI support to ol.renderer.canvas.TileLayer