Shrink dictionaries on deletion if number of elements are less than a

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 4d1f68dac3922d98fd3908448b1dfc86117c4927..f3dae42247cc1d4dc2b273707c251038661b9f3d 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -2590,6 +2590,12 @@ class HashTable: public FixedArray {
     return (last + number) & (size - 1);
   }
 
+  // Rehashes this hash-table into the new table.
+  MUST_USE_RESULT MaybeObject* Rehash(HashTable* new_table, Key key);
+
+  // Attempt to shrink hash table after removal of key.
+  MUST_USE_RESULT MaybeObject* Shrink(Key key);
+
   // Ensure enough space for n additional elements.
   MUST_USE_RESULT MaybeObject* EnsureCapacity(int n, Key key);
 };
@@ -2754,6 +2760,9 @@ class Dictionary: public HashTable<Shape, Key> {
   // Delete a property from the dictionary.
   Object* DeleteProperty(int entry, JSObject::DeleteMode mode);
 
+  // Attempt to shrink the dictionary after deletion of key.
+  MUST_USE_RESULT MaybeObject* Shrink(Key key);
+
   // Returns the number of elements in the dictionary filtering out properties
   // with the specified attributes.
   int NumberOfElementsFilterAttributes(PropertyAttributes filter);