Reland "Fix property enum cache creation to include only own properties"

test/mjsunit/regress/regress-enum-prop-keys-cache-size.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: --allow-natives-syntax --stress-compaction
+
+%SetAllocationTimeout(100000, 100000);
+
+var x = {};
+x.a = 1;
+x.b = 2;
+x = {};
+
+var y = {};
+y.a = 1;
+
+%SetAllocationTimeout(100000, 0);
+
+for (var z in y) { }