Fixes https://github.com/fdorg/flashdevelop/issues/444

Also discovered that the ASFileParser does not seem to play nice with stuff like

    public function test(p_str:String = "let's use \"quotation marks\" in a string!"):void

But that thing looked far too monolithic and scary to attempt working that out...
Anyways, for the issue posted in the forum, this fix should be fine, and if the ASFileParser gets an update to deal with escaped quotation marks inside default parameters, this fix should still be fine since it takes escaping into account :)