[elements] update Dictionary in IncludesValue if own elements change

test/mjsunit/es7/regress/regress-634273.js

+// 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.
+
+// Flags: --enable-slow-asserts
+
+array = new Array(undefined, undefined, undefined);
+Object.defineProperty(array, 0, {
+  get: function() {
+    array.push(undefined, undefined);
+  }
+});
+array[0x80000] = 1;
+result = array.includes(new WeakMap());