title: Ionic collection-repeat issue
body: <p>I used collection-repeat with md-grid-tile below,</p>
  
  <pre><code>    &lt;md-grid-tile collection-repeat="record in records" md-rowspan="1"
   md-colspan="1" md-colspan-sm="1" &gt;
  &lt;!--- Rest of code ---&gt;
  &lt;/md-grid-tile&gt;
  </code></pre>
  
  <p>but when I run this, it will display error like this in console.</p>
  
  <blockquote>
    <p>Error: collection-repeat tried to compute the height of repeated elements "record in records", but was unable to. Please provide the "item-height" attribute</p>
  </blockquote>
  
  <p>Is there any way to fix this issue??</p>