Unify mechanism to find trailing AllocationMementos

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 0f87fd1de8c9e9e09202d20de28a11e5ef2cd11e..442c140232cb15af053837f75dcdca643288a84f 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1461,6 +1461,10 @@ class Heap {
     RECORD_SCRATCHPAD_SLOT
   };
 
+  // If an object has an AllocationMemento trailing it, return it, otherwise
+  // return NULL;
+  inline AllocationMemento* FindAllocationMemento(HeapObject* object);
+
   // An object may have an AllocationSite associated with it through a trailing
   // AllocationMemento. Its feedback should be updated when objects are found
   // in the heap.