Switch to aggresive promotion in mark-sweep collections.

src/mark-compact.cc

Index: src/mark-compact.cc
===================================================================
--- src/mark-compact.cc	(revision 4452)
+++ src/mark-compact.cc	(working copy)
@@ -1210,8 +1210,8 @@
       size = object->Size();
       survivors_size += size;
 
-      if (Heap::ShouldBePromoted(current, size) &&
-          TryPromoteObject(object, size)) {
+      // Aggressively promote young survivors to the old space.
+      if (TryPromoteObject(object, size)) {
         continue;
       }