<apex:page showHeader="false" showChat="false" sidebar="false" standardStylesheets="false">
    <script type="text/javascript">
    	// URL must be prefixed with http:// or https://
    	// otherwise it will be considered a relative URL in your Salesforce instance
    	// e.g. https://<your_instance>.visual.force.com/apex/www.google.com
    	window.location = 'https://www.google.com';
    </script>
</apex:page>