AccessibleSlider: issue with keyboardStep and constrainValue

[jessegreenberg]

@jbphet discovered that combinations of options of constrainValue and keyboardStep can result in a slider that is not usable with the keyboard. For example, if the keyboardStep is small enough such that constrainValue will round the value back to what it was before the change, arrow keys will do nothing.

@jbphet recommended throwing an assertion to warn of this case.

[jessegreenberg]

I added the assertion, test-sims.html hit the assertion in the following sims/runnables:

• hookes-law
• masses-and-springs
• pendulum-lab
• projectile-motion
• tambo (issue was first noted here)
• wave-interference
• wave-on-a-string

[zepumph]

This is a really great thought! But over in #837 we are going nuclear and getting rid of constraintValue entirely. Closing