[svn r328] Fixed an issue with interfaces where the vtable type of a interface implemented could be invalid. Fixes several tango modules like, FileStream, ServerSocket and most tina cluster modules :)

module bug7;

class love { }
void bug() {
    love[] child;
    child.length=1;
    assert(child[0] is null);
    child[0]=null;
    assert(child[0] is null);
}
void main()
{
    bug();
}