cleanup: Require "dangling" commas

Since ES5, trailing commas in arrays and object literals are valid.
We generally haven't used them so far, but they are actually a good
idea, as they make additions and removals in diffs much cleaner.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/805

js/misc/modemManager.js

@@ -218,7 +218,7 @@ var BroadbandModem = GObject.registerClass({
             'capabilities', 'capabilities', 'capabilities',
             GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY,
             NM.DeviceModemCapabilities.$gtype,
-            NM.DeviceModemCapabilities.NONE)
+            NM.DeviceModemCapabilities.NONE),
     },
 }, class BroadbandModem extends ModemBase {
     _init(path, capabilities) {