AnalyticalGraphicsInc/cesium — pull request #524 by kring (2013-02-18 15:34:12+00:00)
Title: Fix faulty logic in Extent.isEmpty.

An extent should be considered empty if either `west >= east` OR `south >= north`. Both need not be true.

I considered requiring that `west > east`, so a point or a line is considered a valid extent. This would be break the only user of this method though, `Polygon`, and I can argue this either way, so I ended up bailing on it.