* lisp/emacs-lisp/edebug.el: Use backtrace-eval to handle lexical variables.

* lisp/emacs-lisp/edebug.el: Use backtrace-eval to handle lexical variables.
(edebug-eval): Use backtrace-eval.
(edebug--display, edebug--recursive-edit): Don't let-bind the
edebug-outer-* vars that keep track of variables we locally let-bind.
(edebug-outside-excursion): Don't restore outside values of locally
let-bound vars.
(edebug--display): Use user-error.
(cl-lexical-debug, cl-debug-env): Remove.