bug#25294: 26.0.50; Allow more catch-all values for cl-defmethod's &context plus major-mode specializer

[Eric Abrahamsen]

When defining a method using cl-defmethod with the &context and
major-mode specializer, there should be more acceptable options for
catch-all or fall-through methods. Ie, we want to create a method that
fires regardless of the major mode. These signatures don't work, but
should:

(cl-defmethod example-method ((&context (major-mode fundamental-mode))))

(cl-defmethod example-method ((&context (major-mode nil)))

(cl-defmethod example-method ((&context (major-mode t))))

Right now the only thing that works is:

(cl-defmethod example-method ())



In GNU Emacs 26.0.50.9 (x86_64-unknown-linux-gnu, GTK+ Version 3.22.5)
 of 2016-12-26 built on clem
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