Remove now-incorrect DataView accessor optimization

test/mjsunit/regress/regress-5018.js

Index: test/mjsunit/regress/regress-5018.js
diff --git a/test/mjsunit/regress/regress-5018.js b/test/mjsunit/regress/regress-5018.js
new file mode 100644
index 0000000000000000000000000000000000000000..22025dc2d8c76b36afd31848965f68d708ad9714
--- /dev/null
+++ b/test/mjsunit/regress/regress-5018.js
@@ -0,0 +1,29 @@
+// Copyright 2016 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.
+
+var dv = new DataView(new ArrayBuffer(4), 2);
+
+function getByteLength(a) {
+  return a.byteLength;
+}
+
+assertEquals(2, getByteLength(dv));
+assertEquals(2, getByteLength(dv));
+
+Object.defineProperty(dv.__proto__, 'byteLength', {value: 42});
+
+assertEquals(42, dv.byteLength);
+assertEquals(42, getByteLength(dv));
+
+function getByteOffset(a) {
+  return a.byteOffset;
+}
+
+assertEquals(2, getByteOffset(dv));
+assertEquals(2, getByteOffset(dv));
+
+Object.defineProperty(dv.__proto__, 'byteOffset', {value: 42});
+
+assertEquals(42, dv.byteOffset);
+assertEquals(42, getByteOffset(dv));