Rework leaf calls as just simple C calls with a signature and not the NativeArgumentDescriptor.

vm/runtime_entry_test.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/runtime_entry.h"
 
 #include "vm/object.h"
 #include "vm/verifier.h"
 
 namespace dart {
@@ skipping 25 matching lines @@
   ASSERT(arguments.Count() == kTestSmiSubRuntimeEntry.argument_count());
   const Smi& left = Smi::CheckedHandle(arguments.At(0));
   const Smi& right = Smi::CheckedHandle(arguments.At(1));
   // Ignoring overflow in the calculation below.
   intptr_t result = left.Value() - right.Value();
   arguments.SetReturn(Smi::Handle(Smi::New(result)));
 }
 
 
 // A leaf runtime call for test purposes.
-// Arg0: a smi.
-// Arg1: a smi.
+// arg0: a smi.
+// arg1: a smi.
 // returns a smi representing arg0 + arg1.
-DEFINE_LEAF_RUNTIME_ENTRY(TestLeafSmiAdd, 2) {
-  ASSERT(args.Count() == kTestLeafSmiAddRuntimeEntry.argument_count());
+DEFINE_LEAF_RUNTIME_ENTRY(RawObject*, TestLeafSmiAdd,
+                          RawObject* arg0, RawObject* arg1) {
   // Ignoring overflow in the calculation below and using the internal
   // representation of Smi directly without using any handlized code.
-  intptr_t result = reinterpret_cast<intptr_t>(args.At(0)) +
-      reinterpret_cast<intptr_t>(args.At(1));
+  intptr_t result = reinterpret_cast<intptr_t>(arg0) +
+      reinterpret_cast<intptr_t>(arg1);
   return reinterpret_cast<RawObject*>(result);
 }
+END_LEAF_RUNTIME_ENTRY
 
 }  // namespace dart