"viewed" checkboxes don't always propagate

[alexr00]

1. Check out a PR and mark all the files in a folder as read.
2. Reload.
3. Expected: The parent folder of the files you marked as viewed will be checked.
   Actual: All the children are checked, but the parent is not.

[alexr00]

Found the actual problem. Real repro steps:

1. Open a PR that has folders that get collapsed onto one line. Example (see that folder2 is nested under folder1 but they get shown on one line):
   
2. Mark all the files in the folders as viewed
3. See that the check doesn't get propagated to the parent folder.

[roblourens]

Most of these select the parent folder when all the children are selected, except for the top level