DevTools: [JsDocValidator] Make sure messages are always sorted in the output

Messages were sorted in the order of node post-visits, which occurs inside-out,
so for double-nested functions the message order was reversed.

R=aandrey, eustas, sergeyv, vsevik

Review URL: https://codereview.chromium.org/103753005

git-svn-id: svn://svn.chromium.org/blink/trunk@163953 bbb929c8-8fbe-4397-9dbb-9b2b20218538