Tests that the scrubber is dropped when a video is too narrow and restored when made wider.

EXPECTED (video.controls != 'null') OK
EVENT(canplaythrough)
EXPECTED (shadowRoot = internals.shadowRoot(video) != 'null') OK
EXPECTED (timelineContainer = mediaControlsElement(shadowRoot.firstChild, "-webkit-media-controls-timeline-container") != 'null'), OBSERVED 'null' FAIL
Initital test at width = 200px
EXPECTED (video.offsetWidth == '200') OK
TypeError: null is not an object (evaluating 'timelineContainer.children')
TypeError: null is not an object (evaluating 'timelineContainer.children')
Second test at width = 500px
EXPECTED (video.offsetWidth == '500') OK
TypeError: null is not an object (evaluating 'timelineContainer.children')
TypeError: null is not an object (evaluating 'timelineContainer.children')
END OF TEST