Fall back to indexing a Point in some cases

Index a Point instead of a low-coordinate-count Polygon, which is an indication that our geo manipulations may have gone overboard. This is a stopgap until we improve the detection and resolution of invalid geometries and the simplification of high-coordinate-count geometries.

/cc @hampelm 

Can you add a brief comment that describes what this block does? 

It looks like it ensures that the coordinates are within `Number.[+/-]_INFINITY`? Could this lead to repeated points (and therefore malformed geometries) if multiple coordinates are outside the bounds?