AccessibleValueHandler gives a11yCreateContextResponseAlert incorrect values

[jessegreenberg]

Specifically, the this.oldValue is passed to a11yCreateContextResponseAlert but it is already updated by the time the function is called. I looked into waiting to update the value but I couldn't get there. In particular, the oldValue is set every time the value Property changes. But alertContextResponse is only called once when the drag ends.

I am going to add a new field for the value on interaction start and pass that as the old value to a11yCreateContextResponseAlert.

[jessegreenberg]

No sim is using the args of a11yCreateContextResponseAlert which is why it hasn't been an issue.

[jessegreenberg]

Done in the above commit, it is working well for my needs in greenhouse-effect.