title: ExtJS 4 Object.prototype fail
body: <p>have a bit problem to use prototype while using <code>framework ExtJS version 4.1.1.</code></p>
  
  <p>At first I made my prototypings before I load ExtJS.
  On <code>"Array.prototype.xyz" and "String.prototype.xyz"</code> all work fine.
  Bot on <code>"Object.prototype.xyz"</code> there is a bad behavior in mixin inclusion of <code>ExtJS</code>.
  Example my test code:</p>
  
  <pre><code>Object.prototype.doSomething = function() {
    console.log('I do it!');
  }
  var a = {};
  a.doSomething();
  </code></pre>
  
  <p>Error message from ExtJS: </p>
  
  <pre><code>Uncaught TypeError: Cannot read property '$childEls' of undefined
  And break.
  </code></pre>
  
  <p>And: 
  - Yes. Without "<code>Uncaught TypeError</code>: Cannot read property '$childEls' of undefined" it work 
  fine.
  - No. I use not oter mixins currently.
  - Yes. I try to use only one dummy panel Component.</p>
  
  <p>Question: Is there a simple solution to prototype on Object class-object?</p>