Create read only handles for empty_array and sentinel objects

vm/object_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/assembler.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/isolate.h"
 #include "vm/object.h"
 #include "vm/object_store.h"
 #include "vm/symbols.h"
 #include "vm/unit_test.h"
 
 namespace dart {
 
 TEST_CASE(Class) {
   // Allocate the class first.
   const String& class_name = String::Handle(Symbols::New("MyClass"));
   const Script& script = Script::Handle();
   const Class& cls = Class::Handle(
       Class::New(class_name, script, Scanner::kDummyTokenIndex));
 
   // Class has no fields.
-  const Array& no_fields = Array::Handle(Object::empty_array());
-  cls.SetFields(no_fields);
+  cls.SetFields(Object::empty_array());
 
   // Create and populate the function arrays.
   const Array& functions = Array::Handle(Array::New(6));
   Function& function = Function::Handle();
   String& function_name = String::Handle();
   function_name = Symbols::New("foo");
   function = Function::New(
       function_name, RawFunction::kRegularFunction,
       false, false, false, false, cls, 0);
   functions.SetAt(0, function);
@@ skipping 124 matching lines @@
 
 
 TEST_CASE(InstanceClass) {
   // Allocate the class first.
   String& class_name = String::Handle(Symbols::New("EmptyClass"));
   Script& script = Script::Handle();
   const Class& empty_class =
       Class::Handle(Class::New(class_name, script, Scanner::kDummyTokenIndex));
 
   // No functions and no super class for the EmptyClass.
-  const Array& no_fields = Array::Handle(Object::empty_array());
-  empty_class.SetFields(no_fields);
+  empty_class.SetFields(Object::empty_array());
   empty_class.Finalize();
   EXPECT_EQ(kObjectAlignment, empty_class.instance_size());
   Instance& instance = Instance::Handle(Instance::New(empty_class));
   EXPECT_EQ(empty_class.raw(), instance.clazz());
 
   class_name = Symbols::New("OneFieldClass");
   const Class& one_field_class =
       Class::Handle(Class::New(class_name, script, Scanner::kDummyTokenIndex));
 
   // No functions and no super class for the OneFieldClass.
@@ skipping 1464 matching lines @@
   EXPECT(array.Equals(other_array));
 
   other_array.SetAt(1, other_array);
   EXPECT(!array.Equals(other_array));
 
   other_array = Array::New(kArrayLen - 1);
   other_array.SetAt(0, array);
   other_array.SetAt(2, array);
   EXPECT(!array.Equals(other_array));
 
-  EXPECT_EQ(0, Array::Handle(Object::empty_array()).Length());
+  EXPECT_EQ(0, Object::empty_array().Length());
 }
 
 
 TEST_CASE(StringCodePointIterator) {
   const String& str0 = String::Handle(String::New(""));
   String::CodePointIterator it0(str0);
   EXPECT(!it0.Next());
 
   const String& str1 = String::Handle(String::New(" \xc3\xa7 "));
   String::CodePointIterator it1(str1);
@@ skipping 1817 matching lines @@
   EXPECT_NE(test1.SourceFingerprint(), test3.SourceFingerprint());
   EXPECT_NE(test3.SourceFingerprint(), test4.SourceFingerprint());
   EXPECT_NE(test4.SourceFingerprint(), test5.SourceFingerprint());
   EXPECT_NE(test5.SourceFingerprint(), test6.SourceFingerprint());
   EXPECT_EQ(test6.SourceFingerprint(), test7.SourceFingerprint());
 }
 
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64).
 
 }  // namespace dart