This makes IndentedScope the single point where we can print additional info in
the future, like e.g. AST IDs (at least when the TODOs are fixed). Minor other
cleanups.

R=mvstanton@chromium.org

Review URL: https://codereview.chromium.org/15060005

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14592 ce2b1a6d-e550-0410-aec6-3dcde31c8c00