mbostock/d3 — pull request #1278 by jasondavies (2013-05-28 23:52:20+00:00)
Title: Fix d3.geo.bounds for null geometries.

This fixes an error that would be thrown if no defined bounds were
found. It also ensures that undefined bounds are returned as
[[NaN, NaN], [NaN, NaN]], for consistency with d3.extent, which returns
[undefined, undefined] for an empty array.

Fixes #1154.