Cache Object.create maps on the passed prototype's PrototypeInfo

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index d812c326297ebcf4c081af598dde69ee1da7a313..29aefb21eef0a30fcdb74dee546b75121ed56c0f 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6304,6 +6304,13 @@ class PrototypeInfo : public Struct {
   // [prototype_users]: WeakFixedArray containing maps using this prototype,
   // or Smi(0) if uninitialized.
   DECL_ACCESSORS(prototype_users, Object)
+
+  // [object_create_map]: A field caching the map for Object.create(prototype).
+  static inline void SetObjectCreateMap(Handle<PrototypeInfo> info,
+                                        Handle<Map> map);
+  inline Map* ObjectCreateMap();
+  inline bool HasObjectCreateMap();
+
   // [registry_slot]: Slot in prototype's user registry where this user
   // is stored. Returns UNREGISTERED if this prototype has not been registered.
   inline int registry_slot() const;
@@ -6330,13 +6337,16 @@ class PrototypeInfo : public Struct {
   static const int kPrototypeUsersOffset = HeapObject::kHeaderSize;
   static const int kRegistrySlotOffset = kPrototypeUsersOffset + kPointerSize;
   static const int kValidityCellOffset = kRegistrySlotOffset + kPointerSize;
-  static const int kBitFieldOffset = kValidityCellOffset + kPointerSize;
+  static const int kObjectCreateMap = kValidityCellOffset + kPointerSize;
+  static const int kBitFieldOffset = kObjectCreateMap + kPointerSize;
   static const int kSize = kBitFieldOffset + kPointerSize;
 
   // Bit field usage.
   static const int kShouldBeFastBit = 0;
 
  private:
+  DECL_ACCESSORS(object_create_map, Object)
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(PrototypeInfo);
 };