title: Bing maps is undefined after loading their javascript file
body: <p>I am loading the <a href="http://www.bingmapsportal.com/isdk/ajaxv7#CreateMap1" rel="nofollow">Bing Map API</a> script dynamically. When the script finishes loading, I would like to construct my map. The problem is <code>Microsoft</code> and <code>Microsoft.Maps</code> are defined, but <code>Microsoft.Maps.Map</code> is not. I realize that their script will asynchronously load more scripts, but even after waiting 10 seconds for these additional hypothetical scripts, <code>Microsoft.Maps.Map</code> continues to be undefined. So how do I load their <code>Map</code> class? I see nothing in their <a href="http://www.bingmapsportal.com/isdk/ajaxv7#CreateMap1" rel="nofollow">example</a>, that explicitly loads the class.</p>
  
  <p><strong>Javascript (Prototype Framework):</strong></p>
  
  <pre><code>var script = new Element(
      'script', {
          type: 'text/javascript',
          src: 'http://ecn.dev.virtualearth.net/mapcontrol/mapcontrol.ashx?v=7.0'
      }
  );
  
  script.observe(
      'load',
      function(event) {
          console.info(Microsoft);
          console.info(Microsoft.Maps);
          console.info(Microsoft.Maps.Map);
      }
  );
  
  document.body.appendChild(script);
  </code></pre>
  
  <p><strong>Console Output:</strong></p>
  
  <pre><code>&gt;&gt;&gt;  Microsoft
  Object { Maps={...}}
  &gt;&gt;&gt;  Microsoft.Maps
  Object { Globals={...}}
  &gt;&gt;&gt;  Microsoft.Maps.Map
  undefined
  </code></pre>