elang/compiler/testing: Make |testing::Formatter| not to use |ast::NamespaceBody::owner()| for a preparation of deprecating |ast::Namespace|.
elang/compiler/testing: Make |testing::Formatter| not to use |ast::NamespaceBody::owner()| for a preparation of deprecating |ast::Namespace|.

eval1749/elang,eval1749/elang,eval1749/elang,eval1749/elang,eval1749/elang