Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/spaces.h

Index: src/spaces.h
diff --git a/src/spaces.h b/src/spaces.h
index 43f44a5c707d0c41632215943f2a553296a0f611..2fe45c87d7e13db57d3f0e660474c60a4f24aa0d 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -1714,9 +1714,16 @@ class PagedSpace : public Space {
   Address* allocation_top_address() { return &allocation_info_.top; }
   Address* allocation_limit_address() { return &allocation_info_.limit; }
 
+  enum AllocationType {
+    NEW_OBJECT,
+    MOVE_OBJECT
+  };
+
   // Allocate the requested number of bytes in the space if possible, return a
   // failure object if not.
-  MUST_USE_RESULT inline MaybeObject* AllocateRaw(int size_in_bytes);
+  MUST_USE_RESULT inline MaybeObject* AllocateRaw(
+      int size_in_bytes,
+      AllocationType event = NEW_OBJECT);
 
   virtual bool ReserveSpace(int bytes);
 
@@ -1897,6 +1904,9 @@ class PagedSpace : public Space {
 
   friend class PageIterator;
   friend class SweeperThread;
+
+ private:
+  inline HeapObject* AllocateRawHelper(int size_in_bytes);
 };