Fix: fresh instance of Firefox hangs which opening URL.

Must clone stdin and stdout. This also suppresses the following message spewed by Firefox when a new tab is opened:
----------------
(process:8748): GLib-CRITICAL **: g_slice_set_config: assertion 'sys_page_size == 0' failed
console.error:
  [CustomizableUI]
  Custom widget with id loop-button does not return a valid node
console.error:
  [CustomizableUI]
  Custom widget with id loop-button does not return a valid node
----------------

Signed-off-by: Arun Prakash Jana <engineerarun@gmail.com>

googler

@@ -172,6 +172,8 @@ class Result:
         _stdout = os.dup(1)
         os.close(1)
         fd = os.open(os.devnull, os.O_RDWR)
+        os.dup2(fd, 2)
+        os.dup2(fd, 1)
         try:
             webbrowser.open(self.url)
         finally: