DevTools: normalize the onResize/doResize usage, drive-by sidebar scroller fix.

R=dgozman@chromium.org

Review URL: https://codereview.chromium.org/137143016

git-svn-id: svn://svn.chromium.org/blink/trunk@165941 bbb929c8-8fbe-4397-9dbb-9b2b20218538