Allow rendering of lines and polygons within a clustered GeoJSON source

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**mapbox-gl-js version 0.26.0**:

I'm working on an angular app where it's difficult to know in advance if the GeoJSON data will include points, lines, polygons or any combination of valid GeoJSON features.
### Steps to Trigger Behavior
1. load polygons or lines into a Mapbox GL map
2. on `map.addSource()` set `cluster:true`
3. add a layer of polygons or lines `map.addLayer()`
4. view map in browser
### Expected Behavior

If clustering is turned on, but the data is comprised of lines or polygons, it would be great if the map would still render the valid GeoJSON. If there is a combination of lines, polygons, and points - it would be nice if Mapbox GL would render the lines and polygons normally, while clustering the points as expected.
### Actual Behavior

The map does not render any points, lines, or polygons.

Thank you kindly.

Start by reproducing the behavior in a browser with a GeoJSON source configured through map.addSource() with cluster:true, then add line and polygon layers with map.addLayer(). Verify how points, lines, polygons, and mixed feature collections render. Done means non-point features render normally while point features still cluster as expected.

Written by the indexing model from the issue text.