Sets the Font object from which the font instance's properties are inherited. This method allows for easy standardization and reuse of font styles. For example, a button's normal font can be set to appear in the same style as many default UI elements by setting its font to "GameFontNormal" -- if Blizzard changes the main UI font in a future patch, or if the user installs another addon which changes the main UI font, the button's font will automatically change to match.