Renaming the Scope.watch readOnly argument

[vicb]

When adding a watch, there is a readOnlyargument. The effect of setting readOnly to true is that the watch expression will be evaluated in the flush phase rather than the digest phase.

It should be used when the watch could not result in updating the model and lead to better performance as the expression it evaluated only once instead instead multiple time until the digest converges.

We have been discussing with @mhevery about renaming this argument.

Potential candidates:

• flushPhase
• canChangeModel

The former describes more the implementation, the latter has my preference.

Thoughts ? Any other proposal ?