DevTools: [Console] factually sort messages by timestamp

As per today, console messages are always appended to the end of the
viewport, no matter where they were inserted in the console messages
array according to their timestamp.

This patch makes viewport to reflect console messages order by
doing the following steps:
1. Make console command results to not render their timestamps
2. Set both console commands and console command results messages
such timestamps that they are always appearing in the end of viewport.
3. Schedule updateMessageList if the message was inserted in the middle
of the list.

Review URL: https://codereview.chromium.org/603213002

git-svn-id: svn://svn.chromium.org/blink/trunk@183060 bbb929c8-8fbe-4397-9dbb-9b2b20218538