CloudMade/Leaflet — pull request #972 by domoritz (2012-09-03 22:29:39+00:00)
Title: IsValid for Bounds and LatLngBounds

Implemented isValid() function for Bounds and LatLngBounds. Fixes issue #966. Added specification as well.

Example usage:
```javascript
data = L.geoJson([]); // data may come from user input/ ajax
bounds = data.getBounds()
if (bounds.isValid()) {
map.fitBounds(bounds);
}
```