[DevTools] Vector is replaced by Deque in ConsoleMessageStorage

Vector replaced by Deque. Removed size and at interface from Storage.
Added method to get all messages. Each new function that changes messages in storage, should be part of its interface.

BUG=408121
R=vsevik@chromium.org,aandrey@chromium.org

Review URL: https://codereview.chromium.org/524633002

git-svn-id: svn://svn.chromium.org/blink/trunk@181299 bbb929c8-8fbe-4397-9dbb-9b2b20218538