remote: support arguments of type Date

atom/browser/lib/rpc-server.coffee

@@ -67,6 +67,7 @@ unwrapArgs = (sender, args) ->
       when 'remote-object' then objectsRegistry.get meta.id
       when 'array' then unwrapArgs sender, meta.value
       when 'buffer' then new Buffer(meta.value)
+      when 'date' then new Date(meta.value)
       when 'promise' then Promise.resolve(then: metaToValue(meta.then))
       when 'object'
         ret = v8Util.createObjectWithName meta.name