SIGN IN SIGN UP

Trivial tabs-related fixes (#9191)

Add some commentary around DefaultTabController.initialIndex.
Fix typo (nuull) in TabBar.
Make some asserts more detailed.
I
Ian Hickson committed
8469ef03d80fffe8f6a8869f883716845912fb0d
Parent: fbcade5
Committed by Adam Barth <github@adambarth.com> on 4/5/2017, 3:38:29 AM