Relative subpath uses the wrong starting position

[ColaColin]

Given a path like this:
m 0,0 50,0 0,-50 z m 10,10 -50,-20 20,10
the second subpath should start at the location 10,10. Relative to the first position of the previous subpath. The polyfill starts the second subpath at 60,-40. Relative to the last position of the previous path. This breaks svg that rely on such relative positions.

The polyfill needs to track the first position of the current path and use that position to determine the position of a relative next subpath.

Broken example, left is the polyfill, right is the native implementation: http://jsfiddle.net/z1mxLnp7/7/
Hacky fix, implemented without really fully understanding the whole code of the polyfill, so may fail for some datasets I dont use right now: http://jsfiddle.net/z1mxLnp7/6/