bitovi/canjs — pull request #915 by ccummings (2014-04-29 14:52:01+00:00)
Title: Fix memory leak in can.Map computed properties

The `change` event handler for a computed property should be removed if nobody is listening to it. can.Map keeps track of this by maintaining a `count` property internally.

In `unbind` the `count` property was being incremented instead of decremented so the `count` never reached 0 and the handler would never be removed.