title: Using md-virtual-repeat inside md-select not working?
body: <p>I want to use md-select to display a lot of data to the user. When opening the md-select, the browser freezes. So as a solution i want to use md-virtual repeat inside md-select for better performance. But the code isn(t just working out for me. Am I doing something wrong here?</p>
  
  <pre><code>&lt;md-input-container flex&gt;
    &lt;label&gt;test&lt;/label&gt;
    &lt;md-select ng-model="$ctrl.haha"&gt;
      &lt;md-virtual-repeat-container id="vertical-container"&gt;
        &lt;md-option md-virtual-repeat="item in ctrl.infiniteItems" md-on-demand ng-value="item" ng-selected="$first"&gt;
          {{item}}
        &lt;/md-option&gt;
      &lt;/md-virtual-repeat-container&gt;
    &lt;/md-select&gt;
  &lt;/md-input-container&gt;
  </code></pre>
  
  <hr>
  
  <pre><code>#vertical-container {
    height: 256px;
  }
  </code></pre>
  
  <hr>
  
  <pre><code>this.infiniteItems = {
    numLoaded_: 0,
    toLoad_: 0,
    items: [],
  
    // Required.
    getItemAtIndex(index) {
      if (index &gt; this.numLoaded_) {
        this.fetchMoreItems_(index);
        return null;
      }
      return this.items[index];
    },
  
    // Required.
    getLength() {
      return this.numLoaded_ + 5;
    },
  
    fetchMoreItems_(index) {
      if (this.toLoad_ &lt; index) {
        this.toLoad_ += 20;
        for (let i = 0; i &lt; 10000; i++) {
          this.items.push(i);
        }
        this.numLoaded_ = this.toLoad_;
      }
    }
  };
  </code></pre>