-webkit-font-smoothing: antialiased equivalent in firefox?

Firefox 25+ (2013-10-29) supports a new macOS-only nonstandard CSS property -moz-osx-font-smoothing effectively similar to the WebKit’s -webkit-font-smoothing.

So this code should provide consistent results in Firefox and WebKit:

.example {
    -moz-osx-font-smoothing: grayscale;   /* Firefox */
     -webkit-font-smoothing: antialiased; /* WebKit  */
}

Problem is -webkit-font-smoothing: antialiased, which disable standard sub-pixel font smoothing. Try read this

At one point firefox had a font-smooth, but it's been removed and as far as I know is not included at all in the current track. I did some googling and didn't see any indication that there will be any change to that.

As an alternative you could try a workaround like: http://www.elfboy.com/blog/text-shadow_anti-aliasing/.