Implement Object.is and Number.is[Finite,NaN] functions.

test/mjsunit/mjsunit.js

 // Copyright 2008 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 203 matching lines @@
     }
     if (objectClass == "String" || objectClass == "Number" ||
       objectClass == "Boolean" || objectClass == "Date") {
       if (a.valueOf() !== b.valueOf()) return false;
     }
     return deepObjectEquals(a, b);
   }
 
 
   assertSame = function assertSame(expected, found, name_opt) {
+    // TODO(mstarzinger): We should think about using Harmony's egal operator
+    // or the function equivalent Object.is() here.
     if (found === expected) {
       if (expected !== 0 || (1 / expected) == (1 / found)) return;
     } else if ((expected !== expected) && (found !== found)) {
       return;
     }
     fail(PrettyPrint(expected), found, name_opt);
   };
 
 
   assertEquals = function assertEquals(expected, found, name_opt) {
@@ skipping 112 matching lines @@
     // Fix this when we ditch the old test runner.
     var message = "Fail" + "ure: unreachable";
     if (name_opt) {
       message += " - " + name_opt;
     }
     throw new MjsUnitAssertionError(message);
   };
 
 })();