Make FieldType::None() non-nullptr value to avoid undefined behaviour

test/cctest/test-field-type-tracking.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 #include <utility>
 
 #include "test/cctest/test-api.h"
 
 #include "src/v8.h"
 
 #include "src/compilation-cache.h"
 #include "src/compilation-dependencies.h"
 #include "src/execution.h"
 #include "src/factory.h"
 #include "src/field-type.h"
 #include "src/global-handles.h"
 #include "src/ic/stub-cache.h"
 #include "src/macro-assembler.h"
+#include "src/types.h"
 
 using namespace v8::internal;
 
 
 // TODO(ishell): fix this once TransitionToPrototype stops generalizing
 // all field representations (similar to crbug/448711 where elements kind
 // and observed transitions caused generalization of all field representations).
 const bool IS_PROTO_TRANS_ISSUE_FIXED = false;
 
 
@@ skipping 2373 matching lines @@
   CcTest::InitializeVM();
   v8::HandleScope scope(CcTest::isolate());
 
   Handle<AccessorPair> pair = CreateAccessorPair(true, true);
   TransitionToAccessorConstantOperator transition_op(pair);
 
   SameMapChecker checker;
   TestTransitionTo(transition_op, transition_op, checker);
 }
 
+TEST(FieldTypeConvertSimple) {
+  CcTest::InitializeVM();
+  v8::HandleScope scope(CcTest::isolate());
+  Isolate* isolate = CcTest::i_isolate();
+
+  Zone zone(isolate->allocator());
+
+  CHECK_EQ(FieldType::Any()->Convert(&zone), Type::NonInternal());
+  CHECK_EQ(FieldType::None()->Convert(&zone), Type::None());
+}
 
 // TODO(ishell): add this test once IS_ACCESSOR_FIELD_SUPPORTED is supported.
 // TEST(TransitionAccessorConstantToAnotherAccessorConstant)