How to indent ActionScript associative array with VIM

Question

I'm trying to use VIM to format AS3 codes, but have some problems for object definitions. VIM formats it as below:

    var object = {
a : b,
    c : d
    }

However what I want is

    var object = {
        a : b,
        c : d
        }

In the "C-Indenting" part of VIM manual, it says

Vim puts a line in column 1 if:
* It starts with a label (a keyword followed by ':', other than "case" and "default").

I'm pretty sure this is the reason my codes are not formatted as I expected. Could anyone teach me how to prevent VIM to apply this rule? Thanks ahead.