The idea is to extract all the CodeEvent loggers into separate classes
make an interface for code events and put them into a listeners array.

I extracted code that works with name_buffer into a separate base class CodeEventLogger.
And made JitLogger, LowLevelLogger and new CodeMap its descendants.

As a side effect I converted NameBuffer into nested class of CodeEventLogger
and converted NameMap into nested class of CodeMap.

BUG=260203
R=yangguo@chromium.org, yurys@chromium.org

Review URL: https://codereview.chromium.org/19795002

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@15784 ce2b1a6d-e550-0410-aec6-3dcde31c8c00