[es6] Implement spec compliant ToName (actually ToPropertyKey).

test/mjsunit/harmony/to-name.js

+// Copyright 2015 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.
+
+// Flags: --allow-natives-syntax
+
+assertEquals("1", %ToName(1));
+assertEquals("1", %_ToName(1));
+
+assertEquals("0.5", %ToName(.5));
+assertEquals("0.5", %_ToName(.5));
+
+assertEquals("null", %ToName(null));
+assertEquals("null", %_ToName(null));
+
+assertEquals("true", %ToName(true));
+assertEquals("true", %_ToName(true));
+
+assertEquals("false", %ToName(false));
+assertEquals("false", %_ToName(false));
+
+assertEquals("undefined", %ToName(undefined));
+assertEquals("undefined", %_ToName(undefined));
+
+assertEquals("random text", %ToName("random text"));
+assertEquals("random text", %_ToName("random text"));
+
+assertEquals(Symbol.toPrimitive, %ToName(Symbol.toPrimitive));
+assertEquals(Symbol.toPrimitive, %_ToName(Symbol.toPrimitive));
+
+var a = { toString: function() { return "xyz" }};
+assertEquals("xyz", %ToName(a));
+assertEquals("xyz", %_ToName(a));
+
+var b = { valueOf: function() { return 42 }};
+assertEquals("[object Object]", %ToName(b));
+assertEquals("[object Object]", %_ToName(b));
+
+var c = {
+  toString: function() { return "x"},
+  valueOf: function() { return 123 }
+};
+assertEquals("x", %ToName(c));
+assertEquals("x", %_ToName(c));
+
+var d = {
+  [Symbol.toPrimitive]: function(hint) { return hint }
+};
+assertEquals("string", %ToName(d));
+assertEquals("string", %_ToName(d));