Remove (hopefully) dead download code

If the percentage is None, remaining/total should always be None
too (as percentage/remaining being None should be triggered by total
being None).

qutebrowser/browser/webkit/downloads.py

@@ -352,10 +352,7 @@ class DownloadItem(QObject):
             return ('{index}: {name} [{speed:>10}|{down}]{errmsg}'.format(
                 index=self.index, name=self.basename, speed=speed,
                 down=down, errmsg=errmsg))
-        if perc is None:
-            perc = '??'
-        else:
-            perc = round(perc)
+        perc = round(perc)
         if remaining is None:
             remaining = '?'
         else: