`$watch` misbehaving when used with `v-with`

[jtremback]

Check out this example: http://jsbin.com/nolom/7/edit

The alert is only supposed to fire on changes to the title keypath. However, it fires on any changes to the vm.

[squirmy]

Hi - I have come across the same issue: http://jsfiddle.net/PLep8/

I'm expecting number on both VMs to only update once. But the inner VM's number spins out of control! :)

Looks like it may be a regression, as testing against v0.8.1 works as expected.

[der-david]

Encountered the same problem just now, here's another example: http://jsbin.com/xibadixa/1/edit?html,console,output

[yyx990803]

fixed, thanks for the examples guys!