Create read only handles for empty_array and sentinel objects

vm/code_generator_test.cc

 // Copyright (c) 2012, 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 "platform/assert.h"
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64)
 
 #include "vm/ast.h"
 #include "vm/assembler.h"
@@ skipping 529 matching lines @@
 
   const TypeArguments& no_type_arguments = TypeArguments::ZoneHandle();
   ArgumentListNode* no_arguments = new ArgumentListNode(kPos);
   const LocalVariable* allocated = test->CreateTempConstVariable("alloc");
   test->node_sequence()->Add(new ReturnNode(kPos, new ConstructorCallNode(
       kPos, no_type_arguments, constructor, no_arguments, allocated)));
 }
 
 
 CODEGEN_TEST_RAW_RUN(AllocateNewObjectCodegen, function) {
-  const Array& args = Array::Handle(Object::empty_array());
-  const Object& result = Object::Handle(DartEntry::InvokeStatic(function,
-                                                                args));
+  const Object& result = Object::Handle(
+      DartEntry::InvokeStatic(function, Object::empty_array()));
   EXPECT(!result.IsError());
   const GrowableObjectArray& libs =  GrowableObjectArray::Handle(
       Isolate::Current()->object_store()->libraries());
   ASSERT(!libs.IsNull());
   // App lib is the last one that was loaded.
   intptr_t num_libs = libs.Length();
   Library& app_lib = Library::Handle();
   app_lib ^= libs.At(num_libs - 1);
   ASSERT(!app_lib.IsNull());
   const Class& cls = Class::Handle(
       app_lib.LookupClass(String::Handle(Symbols::New("A"))));
   EXPECT_EQ(cls.raw(), result.clazz());
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32 || defined(TARGET_ARCH_X64)