Make == for associative arrays test for equality, not identity. _aaEq was added to runtime/internal/aaA.d which forwards to TypeInfo_AssociativeArray.equals in genobj.d. On the codegen side, DtoAAEquals was added to gen/aa.cpp and is called from EqualExp::toElem in gen/toir.cpp. I assume that the frontend will produce an error if == is used on associative arrays of different type. This fixes DMD bug 1429.

module arrays3;

void main()
{
    int[] arr;
    {arr = new int[25];}
    {assert(arr.length == 25);}
    {arr.length = arr.length + 5;}
    {assert(arr.length == 30);}
}