Support the following case:

src/hotspot/share/opto/doCall.cpp:
    if (receiver_type == NULL || !receiver_type->higher_equal(mr_type)) {
      // Calling this method would include an implicit cast to its holder.
      // %%% Not yet implemented.  Would throw minor asserts at present.
      // %%% The most common wins are already gained by +UseUniqueSubclasses.
      // To fix, put the higher_equal check at the call of this routine,
      // and add a CheckCastPP to the receiver.