Use the return value of vm native methods to set the return value,

vm/stub_code_ia32_test.cc

Index: vm/stub_code_ia32_test.cc
===================================================================
--- vm/stub_code_ia32_test.cc	(revision 11528)
+++ vm/stub_code_ia32_test.cc	(working copy)
@@ -122,9 +122,7 @@
   const Smi& smi1 = Smi::ZoneHandle(Smi::New(value1));
   const Smi& smi2 = Smi::ZoneHandle(Smi::New(value2));
   const Object& result = Object::ZoneHandle();
-  const String& native_name = String::ZoneHandle(String::New("TestSmiSub"));
-  Dart_NativeFunction native_function =
-      NativeTestEntry_Lookup(native_name, argc);
+  Dart_NativeFunction native_function = TestSmiSub;
   ASSERT(native_function != NULL);
   const Context& context = Context::ZoneHandle(Context::New(0, Heap::kOld));
   ASSERT(context.isolate() == Isolate::Current());