shelf: Remove accidently left behind testing code.

Used this to display the overflow bubble more easily.

R=msw@chromium.org

Test: manual
Bug: 863822
Change-Id: Id7cb6147c5ce4b699ed5c3573ab23388cdb0b465
Reviewed-on: https://chromium-review.googlesource.com/1138404
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575365}
2 files changed