Creating a PlaneGeometry with too many height/width units crashes dartium.

In both checked and unchecked mode, this line is enough to crash dartium:

```
  final planeGeo = new three.PlaneGeometry(5000.0, 5000.0, 1000, 1000);
```

I'm doing this is threejs with no problems, see: http://dnmfd16oyg4vb.cloudfront.net/
