mbostock/d3 — pull request #1356 by mbostock (2013-07-02 00:51:55+00:00)
Title: Use linear segments for basis interpolation ends.

The first and last segment of a line interpolated using basis (B-spline) interpolation are necessarily linear. WebKit appears to have a bug where linear Bézier segments do not compute tangents correctly (presumably because the control points are coincident with an end point, and the angle of a zero-length vector is undefined). We can workaround this browser bug by using linear segments for the start and end.