This makes --gc-sections perform better, as the GC operates on whole sections.  This makes a worthwhile binary size decrease in the Chromium Linux build.

Review URL: http://codereview.chromium.org/18803


git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@1164 ce2b1a6d-e550-0410-aec6-3dcde31c8c00