Allow direct allocation in old pointer space.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 7e5a4e8f7e3c20060da1cb6a6111358a76547fa7..01b361922fc0b3370190de57c2543dea9049afcc 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -591,6 +591,13 @@ class Heap {
     return new_space_.allocation_limit_address();
   }
 
+  Address* OldPointerSpaceAllocationTopAddress() {
+    return old_pointer_space_->allocation_top_address();
+  }
+  Address* OldPointerSpaceAllocationLimitAddress() {
+    return old_pointer_space_->allocation_limit_address();
+  }
+
   // Uncommit unused semi space.
   bool UncommitFromSpace() { return new_space_.UncommitFromSpace(); }