When an element has text-rendering: optimizeLegibility the text sometimes wraps if it has a single space in it.
It happens when the element is also floated (either left or right), has a specific font (sans-serif) and a specific font-size (15px)
While I can’t reproduce this in Yosemite on a Retina display, this sort of bug is usually the result of inconsistent behavior of the complex text code path.
Which Windows port are you using?
I use Windows 7 64 bit and I couldn't reproduce it on my Macbook in Yosemite. And it only happens on Chrome 39, not 38.