openlayers/ol3 — pull request #1423 by twpayne (2013-12-20 13:50:22+00:00)
Title: [vector-api] Handle features with null geometries

In the `vector-api` branch, it is fine for a feature to have a geometry which is `null`.

This PR improves the handling of such features. Notably:
* Rendering a feature with a `null` geometry has no effect
* `ol.source.Vector` properly handles changes feature's geometry to and from `null`

CC @fgravin