[turbofan] Restore basic write barrier elimination.

test/cctest/test-unboxed-doubles.cc

Index: test/cctest/test-unboxed-doubles.cc
diff --git a/test/cctest/test-unboxed-doubles.cc b/test/cctest/test-unboxed-doubles.cc
index 7fc9b5beec55c8d4d67c3973962f118ae9e0cf92..39f8fbf3403d3be2a429317284e3e0179d7bdffa 100644
--- a/test/cctest/test-unboxed-doubles.cc
+++ b/test/cctest/test-unboxed-doubles.cc
@@ -1504,10 +1504,12 @@ static void TestIncrementalWriteBarrier(Handle<Map> map, Handle<Map> new_map,
   CHECK_EQ(boom_value, obj->RawFastDoublePropertyAt(double_field_index));
 }
 
-
-enum WriteBarrierKind { OLD_TO_OLD_WRITE_BARRIER, OLD_TO_NEW_WRITE_BARRIER };
+enum OldToWriteBarrierKind {
+  OLD_TO_OLD_WRITE_BARRIER,
+  OLD_TO_NEW_WRITE_BARRIER
+};
 static void TestWriteBarrierObjectShiftFieldsRight(
-    WriteBarrierKind write_barrier_kind) {
+    OldToWriteBarrierKind write_barrier_kind) {
   CcTest::InitializeVM();
   Isolate* isolate = CcTest::i_isolate();
   v8::HandleScope scope(CcTest::isolate());