The sub-pixel antialiasing of light text on a dark background in OSX is horrendously broken and has been horrendously broken forever.
There may be a way to use the font smoothing options in Chrome to counteract this problem but the way I work around this is to choose fonts that have a number of weights and substitute lighter weights when rendering text on a dark background. Source Sans Pro, Merriweather and Source Code Pro are good open source fonts that have this property.