Webkit only returns the first specified font in a font-family declaration as Computed Value, regardless of what font is actually used / what fonts are available. See URL for test case with a custom font that you probably won't have on your system. The W3C Fonts spec says that the Computed Value should be "as specified": http://www.w3.org/TR/CSS21/fonts.html#font-family-prop
The relevant test case doesn't seem available anymore.