Provide a tagged allocation top pointer.

test/cctest/heap/heap-utils.h

Index: test/cctest/heap/heap-utils.h
diff --git a/test/cctest/heap/heap-utils.h b/test/cctest/heap/heap-utils.h
index e03e6fa6e0461df12f6ec8a204a9975b782d09c8..1954cf2ed9899b2451c46225c663f1deb52583f4 100644
--- a/test/cctest/heap/heap-utils.h
+++ b/test/cctest/heap/heap-utils.h
@@ -44,6 +44,9 @@ void AbandonCurrentlyFreeMemory(PagedSpace* space);
 
 void GcAndSweep(Heap* heap, AllocationSpace space);
 
+// Helper function to make sure that the new space's top is not double-aligned.
+void MakeSureNewSpaceTopIsNotDoubleAligned(i::Heap* heap);
+
 }  // namespace heap
 }  // namespace internal
 }  // namespace v8