Fix DIM hanging when trying to show record books

[bhollis]

#1014 made a change to how we display objective rows, and included code to display a bubble for each Trials win. It did this with an ng-repeat over the range of an objective's completionValue. Unfortunately, in the RoI record book are objectives with completion values that can be in the thousands. This causes us to allocate a thousands-long array and then evaluate the template thousands of times. There's an ng-if making sure each of these doesn't get put into the document, but it's too late - it only happens after each element in the ng-repeat. Wrapping the items in a div that has the ng-if case (actually ng-switch, which fits better here) means we evaluate trials-ness only once per objective.

Fixes #1142.

/cc @kyleshay

[kyleshay]

whooops :) thanks for catching that.