;;; make Chrome/Firefox/Opera extensions loadable like any other archive files:
(setq auto-mode-alist
  (append '(("\\.crx\\'" . archive-mode)
            ("\\.xpi\\'" . archive-mode)
            ("\\.oex\\'" . archive-mode))
          auto-mode-alist))

(setq auto-coding-alist
  (append '(("\\.crx\\'" . no-conversion)
            ("\\.xpi\\'" . no-conversion)
            ("\\.oex\\'" . no-conversion))
          auto-coding-alist))