From Everything.Sucks
ClearType is Microsoft's implementation of subpixel rendering technology in rendering text in a font system. ClearType attempts to improve the appearance of text on certain types of computer display screens by sacrificing color fidelity for additional intensity variation. This trade-off is asserted to work well on LCD flat panel monitors.
On June 21, 2011, x-skeww wrote a comment on a REDDIT discussion about ClearType:
"That bug was fixed a few weeks ago. And more precisely: Chrome used Skia (-> old-school gray-scale antialiasing) for the font-rendering if a text-shadow was used. This quirk allowed you to make big headlines (something ClearType really sucks at) look better by adding a fully transparent text-shadow."