Create read only handles for empty_array and sentinel objects

vm/stub_code_x64_test.cc

Index: vm/stub_code_x64_test.cc
===================================================================
--- vm/stub_code_x64_test.cc	(revision 16415)
+++ vm/stub_code_x64_test.cc	(working copy)
@@ -70,9 +70,8 @@
   const Code& code = Code::Handle(Code::FinalizeCode(
       *CreateFunction("Test_CallRuntimeStubCode"), &_assembler_));
   const Function& function = RegisterFakeFunction(kName, code);
-  const Array& args = Array::Handle(Object::empty_array());
   Smi& result = Smi::Handle();
-  result ^= DartEntry::InvokeStatic(function, args);
+  result ^= DartEntry::InvokeStatic(function, Object::empty_array());
   EXPECT_EQ((value1 - value2), result.Value());
 }
 
@@ -104,9 +103,8 @@
   const Code& code = Code::Handle(Code::FinalizeCode(
       *CreateFunction("Test_CallLeafRuntimeStubCode"), &_assembler_));
   const Function& function = RegisterFakeFunction(kName, code);
-  const Array& args = Array::Handle(Object::empty_array());
   Smi& result = Smi::Handle();
-  result ^= DartEntry::InvokeStatic(function, args);
+  result ^= DartEntry::InvokeStatic(function, Object::empty_array());
   EXPECT_EQ((value1 + value2), result.Value());
 }