Add warning message when using console.markTimeline

Blink supports both console.timeStamp and console.markTimeline. But they do the exact same thing.
This patch prints out the warning message when using console.markTimeline for WebKit/Firebug compatibility.
https://developers.google.com/chrome-developer-tools/docs/console-api

Review URL: https://chromiumcodereview.appspot.com/22340004

git-svn-id: svn://svn.chromium.org/blink/trunk@155819 bbb929c8-8fbe-4397-9dbb-9b2b20218538