Factor out ol.geom.Circle#getRadiusSquared_
Use getRadiusSquared_ in ol.geom.Circle#containsXY
Add stability annotation to ol.Object#getProperties
Add stability annotation to ol.Observable
Add stability annotation to ol.geom.Geometry
Add stability annotation to ol.geom.SimpleGeometry
Add stability annotation to ol.geom.Point
Add stability annotation to ol.geom.LineString
Merge pull request #1624 from twpayne/clean-up-circle

Minor ol.geom.Circle clean-ups
Add stability annotation to ol.geom.LinearRing
Add stability annotation to ol.geom.Polygon
Add stability annotation to ol.geom.MultiPoint
Add stability annotation to ol.geom.MultiLineString
Add stability annotation to ol.geom.MultiPolygon
Add stability annotation to ol.geom.GeometryCollection
Add stability annotation to ol.geom.Circle
Add stability annotation to ol.style.Circle
Add stability annotation to ol.Feature
Add stability annotation to ol.format.GeoJSON
Add stability annotation to ol.format.GPX