DevTools: NetworkPanel: make websocket frames table "live".

1) Fix "estimated" row height.
2) Make "time" column sortable.
3) Make table stick to bottom.
4) Add new frames as they arrive.

BUG=142280

Review URL: https://codereview.chromium.org/643873003

git-svn-id: svn://svn.chromium.org/blink/trunk@183796 bbb929c8-8fbe-4397-9dbb-9b2b20218538