C2: inlining through MH linkers drops speculative part of argument types

CallGenerator::for_method_handle_inline() casts MH linker (MH::linkTo*) arguments before attempting inlining. If any argument has a speculative type attached, it is lost.

CallGenerator* CallGenerator::for_method_handle_inline(JVMState* jvms, ciMethod* caller, ciMethod* callee, bool& input_not_const) {
...
  case vmIntrinsics::_linkToVirtual:
  case vmIntrinsics::_linkToStatic:
  case vmIntrinsics::_linkToSpecial:
  case vmIntrinsics::_linkToInterface:
...
        // Cast reference arguments to its type.
        for (int i = 0, j = 0; i < signature->count(); i++) {
          ciType* t = signature->type_at(i);
          if (t->is_klass()) {
            Node* arg = kit.argument(receiver_skip + j);
            const TypeOopPtr* arg_type = arg->bottom_type()->isa_oopptr();
            const Type* sig_type = TypeOopPtr::make_from_klass(t->as_klass());
            if (arg_type != NULL && !arg_type->higher_equal(sig_type)) {
              Node* cast_obj = gvn.transform(new CheckCastPPNode(kit.control(), arg, sig_type));
              kit.set_argument(receiver_skip + j, cast_obj);
            }
          }
          j += t->size(); // long and double take two slots
        }