Oct 28 2015
d="m 209.57067,821.56629 c 0,0 -14.05776,36.08917 -29.21747,46.19654 -22.72914,15.15412 -80.782534,13.80346 -80.782534,13.80346"
means a zero-length Bezier handle at each end of the line. That's sort of bogus, but is what you get by default in some draw programs, including Inkscape. The SVG spec is ambiguous about this. The renderers which get it wrong seem to get it right for the line end, but wrong for the the line start. Thanks.
More info: This problem occurs when one Bezier handle at the end of a line has zero length. This is unusual, but should work. A path like this:
This turns out to be a known bug in Google Chrome. See https://code.google.com/p/chromium/issues/detail?id=450368
Firefox, Inkscape, and LibreOffice Writer get it right.
Oct 27 2015
All this is on Linux; haven't tried a Windows machine yet.
So who's backwards?