bug#7369: 24.0.50; browse-url prompts should say what browser the will use

[jidanni]

Commands like
   (defun browse-url-firefox (url &optional new-window)
    "Ask the Firefox WWW browser to load URL.
   Default to the URL around or before point.  The strings in
   variable `browse-url-firefox-arguments' are also passed to
   Firefox.

Should (optionally, enabled by default) put in their prompt,
  (interactive (browse-url-interactive-arg "URL: "))
some indication of which program they are about to call.

E.g., instead of URL, say "Call firefox on:" or "Firefox:" or
"URL for Firefox:".

Why? Because otherwise it looks just like the w3m-view-this-url etc.
default prompts, even if one knows which function he is calling.

(emacs-snapshot package, version 1:20101030-1)