Bug 1047283 - [Calendar] Drawer /Add event/ Display event should not play scrolling animation

I'm not sure, but maybe we can just use the `this.baseDate` instead of a new property.. (maybe convert `baseDate` into a setter/getter if needed). It starts getting tricky to understand the code when we have too many variables/properties holding state, specially when value can be set in multiple places, it's easier to introduce errors...