Just any property that has a preset number of values show up as options as you type. The difference is that Chrome shows a dropdown list while with Firefox you have to sort of remember the values as it does an autocomplete. I see no reason Firefox couldn't offer the dropdown since it clearly knows the possible values.

By the way, I tried the same font thing in Chrome and it responded the same way, no font list. You can see a similar behavior with color, for the value it shows possible colors by name. Start your color with # and suddenly there's no options. If there are too many possibilities to list it doesn't list anything.