Cleaning WebDOMActivityLogger interface. Deprecating old methods. Fixing assignment of ActivityLogger to V8PerContextData.

BUG=366916

Review URL: https://codereview.chromium.org/315373002

git-svn-id: svn://svn.chromium.org/blink/trunk@175678 bbb929c8-8fbe-4397-9dbb-9b2b20218538