Clean up some suspicious code. There's no guarantee a constant of integer type is a ConstantInt, so it's not safe to just cast<> these to ConstantInt. (It could be a constant expression, for example) The code is shorter this way too :).

module arrays5;
void main()
{
    auto arr = new float[5];
    {arr[4] = 1f;}
    {assert(arr[0] !<>= 0f);}
    {assert(arr[1] !<>= 0f);}
    {assert(arr[2] !<>= 0f);}
    {assert(arr[3] !<>= 0f);}
    {assert(arr[4] == 1f);}
}