Changes "is" and equality checks to strictly check for primitive types, fix a couple of

compiler/lib/implementation/rtt.js

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // The following methods are used to handle type information
 //
 
 /** 
  * @constructor
  * @param {string} classkey
@@ skipping 251 matching lines @@
  */
 function $cls(cls) {
   return "cls:" + cls;
 }
 
 /**
  * @param {*} o
  * @return {boolean}
  */
 function $isBool(o) {
-  return typeof o == 'boolean' || o instanceof Boolean;
+  return typeof o == 'boolean';
 }
 
 /**
  * @param {*} o
  * @return {boolean}
  */
 function $isNum(o) {
-  return typeof o == 'number' || o instanceof Number;
+  return typeof o == 'number';
 }
 
 /**
  * @param {*} o
  * @return {boolean}
  */
 function $isString(o) {
-  return typeof o == 'string' || o instanceof String;
+  return typeof o == 'string';
 }