The flag restricts hydrogen.cfg output to functions passing the filter,
similar to what --hydrogen-filter does for optimization in general.

This is useful for investigating large repro cases where tracing all
functions would lead to an impractically large hydrogen.cfg file, but
restricting optimization using --hydrogen-filter is undesirable
(e.g. because it might cause the issue to no longer reproduce).

R=mstarzinger@chromium.org

Review URL: https://codereview.chromium.org/22926025

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16302 ce2b1a6d-e550-0410-aec6-3dcde31c8c00