DistanceDisplayCondition bug

Reported on the forum: https://groups.google.com/forum/#!topic/cesium-dev/_LuFSZG0A3k

The corridor with the `DistanceDisplayCondition` will never show up. (I put a skinner corridor at the same positions so you can see where it's supposed to be)

The `DistanceDisplayCondition` will work with the range (0, 1000)

``` javascript
var viewer = new Cesium.Viewer('cesiumContainer');

viewer.entities.add({
corridor : {
positions : Cesium.Cartesian3.fromDegreesArray([
-105.0, 40.0,
-110.0, 40.0,
-110.0, 35.0
]),
width : 200000.0,
material : Cesium.Color.BLUE.withAlpha(0.5),
distanceDisplayCondition: new Cesium.DistanceDisplayCondition(1000, 10000)
}
});

viewer.entities.add({
corridor : {
positions : Cesium.Cartesian3.fromDegreesArray([
-105.0, 40.0,
-110.0, 40.0,
-110.0, 35.0
]),
width : 20000.0,
material : Cesium.Color.BLUE.withAlpha(0.5)
}
});
viewer.zoomTo(viewer.entities);
```

Start by reproducing the supplied Cesium Viewer example with the corridor and DistanceDisplayCondition range (1000, 10000), comparing it with the working (0, 1000) range. Trace the corridor display-condition handling; done when the corridor appears for the documented range while preserving the existing working behavior.

Written by the indexing model from the issue text.