Add validation of contextuals passed to a context object for a passivating scope

6.6.1 Passivation capable beans:

An implementation of Contextual that is not a bean is passivation capable if it implements both PassivationCapable and Serializable.

6.6.4 Passivating scopes

A passivating scope requires that implementations of Contextual passed to any context object for the scope are passivation capable.

Theoretically an implementation of Contextual that is not a bean may be passed to a context object of a passivating scope (e.g. @SessionScoped). The spec should specify what happens then. Apparently the container should detect the problem and treat it as a deployment problem.