{Client}: Mastery Selection Bug in Team Builder

Steps to Reproduce:

1. Enter Teambuilder
2. Select a role and lane
3. Select "View Profile" for one of the people on your friends list and then look at their masteries.
4. Return to the teambuilder interface and pick a champion.
5. Now try to pick masteries. It may or may not display the names of your friend's mastery pages, but when you try to pick a page, it attempts to select the page with the same number from your friend, going as far as displaying the name of that page, then throws an error (i.e. if you pick your first mastery page, it tries to use your friend's first mastery page).

The issue disappears if you leave teambuilder and start over, but seems to be 100% reproducible. I'm on a mid 2014 Macbook Pro 13" Retina. So far, the champion you pick doesn't seem to matter, but I've only tested it with the support role selection.