Improve support of remote files in browse-url.el

* etc/NEWS: Mention support of remote file browsing.

* lisp/net/browse-url.el (browse-url-of-buffer): Revert last change.
(browse-url-of-file): Use temporary file in case of remote file.
(Bug#48397)

etc/NEWS

@@ -1599,6 +1599,11 @@ symbol property to the browsing commands.  With a new command
 'browse-url-with-browser-kind', an URL can explicitly be browsed with
 either an internal or external browser.
 
+---
+*** Support for browsing of remote files.
+If a remote file is taken, a local temporary copy of that file is
+passed to the browser.
+
 *** Support for the conkeror browser is now obsolete.
 
 *** Support for the Mosaic browser has been removed.

lisp/net/browse-url.el

@@ -47,6 +47,7 @@
 ;; browse-url-xdg-open                freedesktop.org xdg-open
 ;; browse-url-kde                     KDE konqueror (kfm)
 ;; browse-url-elinks                  Elinks      Don't know (tried with 0.12.GIT)
+;; eww-browse-url                     Emacs Web Wowser
 
 ;; Browsers can cache Web pages so it may be necessary to tell them to
 ;; reload the current page if it has changed (e.g., if you have edited
@@ -773,6 +774,8 @@ interactively.  Turn the filename into a URL with function
 	  (cond ((not (buffer-modified-p)))
 		(browse-url-save-file (save-buffer))
 		(t (message "%s modified since last save" file))))))
+  (when (file-remote-p file)
+    (setq file (file-local-copy file)))
   (browse-url (browse-url-file-url file))
   (run-hooks 'browse-url-of-file-hook))
 
@@ -806,7 +809,6 @@ narrowed."
 		(or buffer-file-name
 		    (and (boundp 'dired-directory) dired-directory)))))
       (when (or (not file-name)
-                (file-remote-p file-name)
                 ;; This can happen when we're looking at a file from a
                 ;; zip file buffer, for instance.
                 (not (file-exists-p file-name)))