Mutation observer triggered heavily

[NathanC]

In v0.2, the mutation observer gets triggered for every character change in a text area. This is not intended, and has a large impact—I had a memory leak, and while it's not clear this was the cause, it seems likely.

If we can restrict the mutation observation to a smaller top level scope that catches all new text areas, or if we can prevent it from being invoked on value change, that would be good.