SimpleSlice now calls [[Get]] before [[Has]] when generating copy

test/mjsunit/regress/regress-3643.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.
+
+var a = [1, 2, 3];
+Object.defineProperty(a, '1', {
+  get: function() { delete this[1]; return undefined; },
+  configurable: true
+});
+var s = a.slice(1);
+assertTrue('0' in s);
+
+// Sparse case should hit the same code as above due to presence of the getter.
+a = [1, 2, 3];
+a[0xffff] = 4;
+Object.defineProperty(a, '1', {
+  get: function() { delete this[1]; return undefined; },
+  configurable: true
+});
+s = a.slice(1);
+assertTrue('0' in s);