What steps will reproduce the problem?
1. Open a code review
2. Use Up/Down keys
What is the expected output?
The page moves up and down
What do you see instead?
Nothing. It doesn't work. Or worse, it will move up and down the file list, jumping from wherever I happen to be on the page.
Also, when diffs are open and I'm trying to review code, I'll often instinctively use Up/Down or j/k to try and move around a small increment (unlike Page Up/Page Down, which move a lot). It would be nice if j/k kept their current mapping and Up/Down were unbound so they did what you would expect them to on an ordinary page. :)