* gc.c (after_gc_sweep, garbage_collect_body): do major GC (full GC)
  before extending heaps.
  TODO: do major GC when there are many old (promoted) objects.
* gc.c (after_gc_sweep): remove TODO comments.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40909 b2dd03c8-39d4-4d8f-98ff-823fe69b080e