Extruded polygons with large height do not show up in 2D

1. Run the [GeoJSON demo](http://localhost:8080/Apps/Sandcastle/index.html?src=GeoJSON%20and%20TopoJSON.html&label=All)
2. On line 54, remove the `/ 50.0` so that population is really big.
3. Hit run and then `Custom Styling`
4. Switch to 2D, the really tall states like Texas, California, and Pennsylvania do not draw.

This problem has been around a while so I'm not marking this as a showstopper, but we should get to is for 1.7

```javascript
var viewer = new Cesium.Viewer('cesiumContainer', {
sceneMode: Cesium.SceneMode.SCENE2D
});
viewer.entities.add({
polygon : {
hierarchy : Cesium.Cartesian3.fromDegreesArray([-108.0, 42.0,
-100.0, 42.0,
-104.0, 40.0]),
extrudedHeight: 50000000.0,
material : Cesium.Color.RED
}
});
```

Start with the GeoJSON demo and reproduce the issue by removing `/ 50.0` on line 54, selecting Custom Styling, and switching to 2D. Then trace the 2D rendering path for the extruded polygon shown in the issue. Done means very tall polygons such as Texas, California, and Pennsylvania render correctly in 2D.

Written by the indexing model from the issue text.