ES6: String(symbol) should work like symbol.toString

test/mjsunit/harmony/private.js

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 65 matching lines @@
   for (var i in symbols) {
     assertSame(Symbol, symbols[i].__proto__.constructor)
     assertSame(Symbol, Object(symbols[i]).__proto__.constructor)
   }
 }
 TestConstructor()
 
 
 function TestToString() {
   for (var i in symbols) {
-    assertThrows(function() { String(symbols[i]) }, TypeError)
+    assertThrows(function() {new String(symbols[i]) }, TypeError)
+    assertEquals(symbols[i].toString(), String(symbols[i]))
     assertThrows(function() { symbols[i] + "" }, TypeError)
     assertTrue(isValidSymbolString(symbols[i].toString()))
     assertTrue(isValidSymbolString(Object(symbols[i]).toString()))
     assertTrue(isValidSymbolString(Symbol.prototype.toString.call(symbols[i])))
     assertEquals(
         "[object Symbol]", Object.prototype.toString.call(symbols[i]))
   }
 }
 TestToString()
 
@@ skipping 252 matching lines @@
   obj[sym] = 1
   freeze(obj)
   obj[sym] = 2
   assertEquals(2, obj[sym])
   assertTrue(delete obj[sym])
   assertEquals(undefined, obj[sym])
 }
 TestSealAndFreeze(Object.seal)
 TestSealAndFreeze(Object.freeze)
 TestSealAndFreeze(Object.preventExtensions)