TimelinePanel: REGRESSION fix for search in timeline panel

BUG=357096
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/236023006

git-svn-id: svn://svn.chromium.org/blink/trunk@171456 bbb929c8-8fbe-4397-9dbb-9b2b20218538