I love that its very simple. Three things:
1) As was mentioned above, the timer should start on release of a key instead of when it is pressed.
2) It would look somewhat nicer if the time was always displayed in the format xx:xx.xxx, i.e, keep the placeholders.
3) As mentioned above, your scrambles produce moves such as L R L. There is more than one way to fix this, but one of the simplest approaches is to break the cube into three axes. (plural for axis... not the weapons) L and R will be one axis, as are U, D and F, B. If you ensure that no letters (RLUDFB) are repeated, and also that there are no more than two consecutive moves of an axis, you will eliminate the double turns.