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

test/mjsunit/es6/symbols.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 94 matching lines @@
     assertTrue(symbols[i] === symbols[i].valueOf())
     assertTrue(Symbol.prototype.valueOf.call(Object(symbols[i])) === symbols[i])
     assertTrue(Symbol.prototype.valueOf.call(symbols[i]) === symbols[i])
   }
 }
 TestValueOf()
 
 
 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)
     assertThrows(function() { String(Object(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]))
   }
 }
@@ skipping 367 matching lines @@
   Realm.shared = symbol1
   assertSame("x1", Realm.eval(realm, "Symbol.keyFor(Realm.shared)"))
 
   var symbol3 = Realm.eval(realm, "Symbol.for('x3')")
   assertFalse(symbol1 === symbol3)
   assertFalse(symbol2 === symbol3)
   assertSame(symbol3, Symbol.for("x3"))
   assertSame("x3", Symbol.keyFor(symbol3))
 }
 TestRegistry()