This patch includes a number of improvements:
* Material page routes now put a repaint boundary inside their transition so
they don't repaint during the transition.
* Heroes that are on a quest now get a repaint boundary so we repaint them
individually.
* I've hoisted the transparent material for the product items up in the widget
tree, which doesn't affect performance but makes the ink splashes reach the
edge of the product cards.
* I've changed the repaint rainbow visualization to make it easier to see
what's going on.
39e759212f