I've seen many of the proposed solutions, but none were quite what I was hoping.
Here's my best hack at this, where the color is transparent, the background and the top text-shadow are the same color with varying opacities, simulating the mask, and the second text-shadow is a darker, more saturated version of the color you actually want (pretty easy to do with HSLA).
(btw, text and styling based upon a dupe thread's OP)