- correctly display time spent in scavenger (it was attributed to 'other' scope).
- display time spent in 'external' scope.

Review URL: http://codereview.chromium.org/7067022

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@8030 ce2b1a6d-e550-0410-aec6-3dcde31c8c00