Enable ES6 unscopables

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 429 matching lines @@
     assertEquals(objectOwnSymbols[i], syms[i * 2])
   }
 }
 TestGetOwnPropertySymbolsWithProto()
 
 
 function TestWellKnown() {
   var symbols = [
     // TODO(rossberg): reactivate once implemented.
     // "hasInstance", "isConcatSpreadable", "isRegExp",
-    "iterator" //, "toStringTag", "unscopables"
+    "iterator", /* "toStringTag", */ "unscopables"
   ]
 
   for (var i in symbols) {
     var name = symbols[i]
     var desc = Object.getOwnPropertyDescriptor(Symbol, name)
     assertSame("symbol", typeof desc.value)
     assertSame("Symbol(Symbol." + name + ")", desc.value.toString())
     assertFalse(desc.writable)
     assertFalse(desc.configurable)
     assertFalse(desc.enumerable)
@@ skipping 32 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()