Console: cleaning up console-related methods on ScriptExecutionContext, second step of many.
(traditionally improves CSP reporting quality)

BUG=277610
R=mkwst@chromium.org

Review URL: https://codereview.chromium.org/22876021

git-svn-id: svn://svn.chromium.org/blink/trunk@156565 bbb929c8-8fbe-4397-9dbb-9b2b20218538