CONSOLE ERROR: line 299: Uncaught TypeError: Cannot read property 'then' of undefined
This is a testharness.js-based test.
Harness Error. harness_status.status = 1 , harness_status.message = Uncaught TypeError: Cannot read property 'then' of undefined
PASS VibrationManager Mojo bindings and mock interfaces are available to tests. 
PASS navigator.vibrate(1234) triggers vibration correctly. 
PASS navigator.vibrate(0) triggers cancel correctly. 
Harness: the test ran to completion.