Keyboard events and ARIA markup added to speed control. Replaced anonymous event handlers by named functions. Menu stays open on mouseleave when a speed entry has focus. In that case, the menu can be closed by clicking anywhere outside of it. [BLD-402, BLD-363]
Merge pull request #2381 from edx/jmclaus/feature_video_speed_control_improved_a11y

Keyboard events and ARIA markup added to speed control