Remove support for Object.observe

test/mjsunit/regress/regress-3315.js

-// Copyright 2014 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.
-//
-// Flags: --harmony-object-observe
-
-var indexZeroCallCount = 0;
-var indexOneCallCount = 0;
-var lengthCallCount = 0;
-var acceptList = {
-  get 0() {
-    indexZeroCallCount++;
-    return 'foo';
-  },
-  get 1() {
-    indexOneCallCount++;
-    return 'bar';
-  },
-  get length() {
-    lengthCallCount++;
-    return 1;
-  }
-};
-
-Object.observe({}, function(){}, acceptList);
-assertEquals(1, lengthCallCount);
-assertEquals(1, indexZeroCallCount);
-assertEquals(0, indexOneCallCount);