Expose string/regexp related public symbols on harmony flag.

src/js/harmony-concat-spreadable.js

Index: src/js/harmony-concat-spreadable.js
diff --git a/src/js/harmony-concat-spreadable.js b/src/js/harmony-concat-spreadable.js
deleted file mode 100644
index c5d906a64224b95f2d6fd16048c2c9076b685e1c..0000000000000000000000000000000000000000
--- a/src/js/harmony-concat-spreadable.js
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2015 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.
-
-(function(global, utils) {
-
-'use strict';
-
-%CheckIsBootstrapping();
-
-var isConcatSpreadableSymbol =
-    utils.ImportNow("is_concat_spreadable_symbol");
-
-utils.InstallConstants(global.Symbol, [
-  // TODO(littledan): Move to symbol.js when shipping
-  "isConcatSpreadable", isConcatSpreadableSymbol
-]);
-
-})