Optimize non-mutation Map and Set operations for String keys

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 911458c3cb68d47532640e8fac6e0d88034350c8..ab8f72545b87a2fcf1723445f3c1cd121091a996 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3901,6 +3901,19 @@ class OrderedHashTable: public FixedArray {
   static const int kNotFound = -1;
   static const int kMinCapacity = 4;
 
+  static const int kNumberOfBucketsIndex = 0;
+  static const int kNumberOfElementsIndex = kNumberOfBucketsIndex + 1;
+  static const int kNumberOfDeletedElementsIndex = kNumberOfElementsIndex + 1;
+  static const int kHashTableStartIndex = kNumberOfDeletedElementsIndex + 1;
+
+  static const int kNumberOfBucketsOffset =
+      kHeaderSize + kNumberOfBucketsIndex * kPointerSize;
+  static const int kNumberOfElementsOffset =
+      kHeaderSize + kNumberOfElementsIndex * kPointerSize;
+
+  static const int kEntrySize = entrysize + 1;
+  static const int kChainOffset = entrysize;
+
  private:
   static Handle<Derived> Rehash(Handle<Derived> table, int new_capacity);
 
@@ -3942,17 +3955,9 @@ class OrderedHashTable: public FixedArray {
     return set(kRemovedHolesIndex + index, Smi::FromInt(removed_index));
   }
 
-  static const int kNumberOfBucketsIndex = 0;
-  static const int kNumberOfElementsIndex = kNumberOfBucketsIndex + 1;
-  static const int kNumberOfDeletedElementsIndex = kNumberOfElementsIndex + 1;
-  static const int kHashTableStartIndex = kNumberOfDeletedElementsIndex + 1;
-
   static const int kNextTableIndex = kNumberOfElementsIndex;
   static const int kRemovedHolesIndex = kHashTableStartIndex;
 
-  static const int kEntrySize = entrysize + 1;
-  static const int kChainOffset = entrysize;
-
   static const int kLoadFactor = 2;
   static const int kMaxCapacity =
       (FixedArray::kMaxLength - kHashTableStartIndex)
@@ -3992,7 +3997,6 @@ class OrderedHashMap:public OrderedHashTable<
     return get(EntryToIndex(entry) + kValueOffset);
   }
 
- private:
   static const int kValueOffset = 1;
 };