Provide private symbols through internal APIs

test/mjsunit/harmony/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 41 matching lines @@
     gc()        // Promote existing symbols and then allocate some more.
   }
 }
 TestNew()
 
 
 function TestType() {
   for (var i in symbols) {
     assertEquals("symbol", typeof symbols[i])
     assertTrue(typeof symbols[i] === "symbol")
+    assertFalse(%SymbolIsPrivate(symbols[i]))
     assertEquals(null, %_ClassOf(symbols[i]))
     assertEquals("Symbol", %_ClassOf(new Symbol(symbols[i])))
     assertEquals("Symbol", %_ClassOf(Object(symbols[i])))
   }
 }
 TestType()
 
 
 function TestPrototype() {
   assertSame(Object.prototype, Symbol.prototype.__proto__)
@@ skipping 270 matching lines @@
   // but not between scavenges.  This must also apply for symbol keys.
   var key = Symbol("key");
   var a = {};
   a[key] = "abc";
 
   for (var i = 0; i < 1000000; i++) {
     a[key] += "a";  // Allocations cause a scavenge.
   }
 }
 TestCachedKeyAfterScavenge();