Comment 11 for bug 58511

The problem with no antialiasing is due to a bug in firefox's default configuration. In order to have antialiasing and hinting, these two settings must be defined in the global rcfile (or hard coded at compile time):

font.FreeType2.enable must be true (it is false now)
font.FreeType2.unhinted must be false (it is true now)

A *temporary fix* is to set those variables correctly in your personal settings by using about:config. This is certainly a bug in firefox's build (hopefully to be corrected with the Beta2 packages).