precision parsing bug, i think?

[tavelli]

using polyline.toGeoJSON, if i pass precision of 5 or omit precision the parsing works fine. but if i try to use precision of 4 it is messing up decimals places of the lat/lon pairs.

example, default precision or precision 5:
response: [-72.99583, 41.92463]

if i specify precision 4
response: [-729.9583, 419.2463]