Remove --harmony-tostring runtime flag

src/js/symbol.js

 // Copyright 2013 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();
 
@@ skipping 66 matching lines @@
 utils.InstallConstants(GlobalSymbol, [
   "hasInstance", hasInstanceSymbol,
   "isConcatSpreadable", isConcatSpreadableSymbol,
   "iterator", iteratorSymbol,
   // TODO(yangguo): expose when implemented.
   // "match", matchSymbol,
   // "replace", replaceSymbol,
   // "search", searchSymbol,
   // "split, splitSymbol,
   "toPrimitive", toPrimitiveSymbol,
-  // TODO(dslomov, caitp): Currently defined in harmony-tostring.js ---
-  // Move here when shipping
-  // "toStringTag", toStringTagSymbol,
+  "toStringTag", toStringTagSymbol,
   "unscopables", unscopablesSymbol,
 ]);
 
 utils.InstallFunctions(GlobalSymbol, DONT_ENUM, [
   "for", SymbolFor,
   "keyFor", SymbolKeyFor
 ]);
 
 %AddNamedProperty(
     GlobalSymbol.prototype, toStringTagSymbol, "Symbol", DONT_ENUM | READ_ONLY);
 
 utils.InstallFunctions(GlobalSymbol.prototype, DONT_ENUM | READ_ONLY, [
   toPrimitiveSymbol, SymbolToPrimitive
 ]);
 
 utils.InstallFunctions(GlobalSymbol.prototype, DONT_ENUM, [
   "toString", SymbolToString,
   "valueOf", SymbolValueOf
 ]);
 
 // -------------------------------------------------------------------
 // Exports
 
 utils.Export(function(to) {
   to.SymbolToString = SymbolToString;
 })
 
 })