ViewTag makes wrong class cast when using locale attribute

When using JSF inside a portlet the locale attribute of the view-tag can not be used because a ClassCastException is thrown.
This is because ViewTag.setProperties(UIComponent component) assumes that getFacesContext().getExternalContext().getRequest() returns a javax.servlet.ServletRequest which is only correct for non-portlets. For portlets it returns an javax.portlet.PortletRequest which can not be casted to javax.servlet.ServletRequest.

See also:
http://java.sun.com/javaee/javaserverfaces/1.0/docs/api/javax/faces/context/ExternalContext.html#getRequest()