allocation to avoid overhead of arena headers that GC does not use. r=brendan git-svn-id: svn://10.0.0.236/trunk@187700 18797224-902f-48f8-a5cc-f745e15eee43
allocation to avoid overhead of arena headers that GC does not use. r=brendan git-svn-id: svn://10.0.0.236/trunk@187700 18797224-902f-48f8-a5cc-f745e15eee43