mozilla-b2g/marionette-js-client — pull request #51 by evanxd (2013-08-20 08:12:11+00:00)
Title: Bug 907061 - [marionette-js-client] The tap function in Element module is not follow the spec

Tap the center of the element when no x and y offsets are given.
http://bugzil.la/907061