Dotcase: Only check for new notifications before displaying them

Rather than check for new notifications on every redraw, only check at
the beginning of each animation cycle (i.e., right before they're
about to be shown). This reduces notification checks from about twice
per second to about every 3 seconds.

Change-Id: Ia53de5bc24f3e41d33bfe5bc7c0f56b284e4d3e8