Node ids are monotonically increasing and looking at them we can
say e.g. when the node was added before another one. We need this
to diagnose sporadic failures of cctest/test-cpu-profiler/CollectCpuProfile

BUG=v8:2628

Review URL: https://codereview.chromium.org/14402014

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14386 ce2b1a6d-e550-0410-aec6-3dcde31c8c00