Fix case where line ends with [ within (

The opening square bracket would be treated as if it were an argument to
a function call delimited by the enclosing parentheses.

This adds square brackets to the already-existing special case which
handles braces in this context.

Examples:

    1.

        var a = [
            x

        but:

        var a = ([
                  x

    2.

        var a = fn({ // braces already handled correctly
            x: y

        but:

        var a = fn([
                    x
Merge pull request #84 from robin-allen/master

Fix case where line ends with [ within (