GitLab

Recalculate overscroll when shrinking the page, so we don't end up with
a scrollbar for the empty space below us.

BUG=none
R=dschuyler@chromium.org
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2382603002
Cr-Commit-Position: refs/heads/master@{#422684}