DevTools: Get rid of WebInspector.PresentationMessage interface

The PresentationConsoleMessage management is moved from UISourceCode
into PresentationConsoleMessageHelper.

R=eustas, vsevik

Review URL: https://codereview.chromium.org/472353002

git-svn-id: svn://svn.chromium.org/blink/trunk@180442 bbb929c8-8fbe-4397-9dbb-9b2b20218538