This composite el resolver will be used at the top level resolver for faces ( {@link Application#getELResolver()}) and jsp (the one we add with {@link JspApplicationContext#addELResolver(javax.el.ELResolver)}. It keeps track of its scope to let the variable resolver {@link VariableResolverImpl} know in which scope it is executed. This isnecessarry to call either the faces or the jsp resolver head.
This implementation does nothing if there is no actual faces context. This is necessarry since we registered our resolvers into the jsp engine. Therefore we have to make sure that jsp only pages where no faces context is available are still working
@author Mathias Broekelmann (latest modification by $Author: bommel $)
@version $Revision: 915763 $ $Date: 2010-02-24 07:24:11 -0500 (Wed, 24 Feb 2010) $