title: Extjs 3.4 ERR_UNKNOWN_URL_SCHEME when calling valid json url
body: <p>Using Extjs 3.4. I have a simple ajax request:</p>
  
  <pre><code> Ext.Ajax.request({
      url: "localhost:3000/offers.json",  
      success: function(response, opts) {
        var obj = Ext.decode(response.responseText);
        console.dir(obj);
     },
     failure: function(response, opts) {
        console.log('server-side failure with status code ' + response.status);
     }
  });
  </code></pre>
  
  <p>The localhost:3000/offers.json is a Rails 4 back-end and it works fine:</p>
  
  <pre><code>$curl localhost:3000/offers.json              
  [{"id":1,"desc":"a description","img_link":"www.google.come","product_link":"www.google.come","code":"927341","price":"20.29","special_price":"13.99","saving":"31.0","created_at":"2014-06-23T15:45:11.404Z","updated_at":"2014-06-23T15:45:11.404Z"}]
  </code></pre>
  
  <p>So the back-end si working. </p>
  
  <p>When i call the json url from my <code>Ext.Ajax.request</code> I have this error in Chrome console:</p>
  
  <pre><code>OPTIONS localhost:3000/offers.json net::ERR_UNKNOWN_URL_SCHEME ext-base.js:21
  i ext-base.js:21
  Ext.lib.Ajax.k.request ext-base.js:21
  Ext.extend.request ext-all-debug.js:4636
  ajaxSearch_function grid-ajax.js:8
  Ext.Button.Ext.extend.onClick ext-all-debug.js:31872
  h ext-all-debug.js:5215
  server-side failure with status code 0 
  </code></pre>
  
  <p>Ideas? </p>