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 456e9d87a99871ade907de6656f8881d9f9792b5..4cbd20c6ff1c9187146e55e6ec79f859d6c24cc4 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -590,6 +590,13 @@ 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(); }