Bug 1023807 - [B2G][Calendar] Month view: Dot does not appears when even...

Implemented as per  Evan Tseng 's review comments


`Array#forEach` accepts a second argument `this`, so you don't need to `.bind` here..

```diff
       dates.forEach(function(date) {
         var dayId = Calc.getDayId(date);
         var count = this._dayToBusyCount[dayId];
         this._setBusyCount(dayId, count + difference);
-      }.bind(this));
+      }, this);
```

`bind` is theoretically slower than passing the context as second argument.