For usage with Portlets, this Servlet is necessary to force the portlet container
to convert the PortletRequest to a ServletRequest, which it has to do when
including a resource via the PortletRequestDispatcher. This allows for reuse
of the entire Servlet-based View support even in a Portlet environment.
The actual mapping of the bridge servlet is configurable in the DispatcherPortlet,
via a "viewRendererUrl" property. The default is "/WEB-INF/servlet/view", which is
just available for internal resource dispatching.