"data.length is null" error when set innerHTML (which has comment nodes) in IE-8 (only happens in compressed version)

I have encountered a JS error when trying to set innerHTML of a node in IE-8 browser.

    <html>
      <head>
      	<meta http-equiv="X-UA-Compatible" content="IE=edge">
      	<meta charset="utf-8" />
      	<script type="text/javascript" src="http://cdnjs.cloudflare.com/ajax/libs/es5-shim/4.0.3/es5-shim.js">    </script>
      	<script type="text/javascript" src="http://cdnjs.cloudflare.com/ajax/libs/es5-shim/4.0.3/es5-sham.js">    </script>
      	<script type="text/javascript" src="http://cdnjs.cloudflare.com/ajax/libs/react/0.12.0/react.min.js"></script>
      </head>
      <body>
      	<div id="container"></div>
      	<div id="contentToCopy" style="display: none">
      	  <!-- a comment node -->  	  
      	  <h5>content to copy</h5>
      	</div>
    <script type="text/javascript">
    var DivContainer = React.createClass({displayName: 'DivContainer',
      getInitialState: function() {
      	return {content: 'hello world'};
      },
      setContent: function(str) {
        this.setState({content: str + '<!-- ' + (+new Date) + ' -->'});
      },
      render: function() {
        return React.createElement("div", {dangerouslySetInnerHTML: {__html: this.state.content || ''}});
      }
    });
    
    var mountNode = document.getElementById('container');
    
    var instance = React.render(React.createElement(DivContainer), mountNode);
    
    instance.setContent(document.getElementById('contentToCopy').innerHTML);
    </script>
    
      </body>
    </html>


However, if loading with the development version, that JS error would not happen. In this case, the `textNode.data` is an `empty string` instead of `undefined` as in compressed version.