Simpler return value from HashTable::add()/HashMap::add() and others

Source/wtf/HashMap.h

Index: Source/wtf/HashMap.h
diff --git a/Source/wtf/HashMap.h b/Source/wtf/HashMap.h
index 551f14974462058f6d189a6071e70d8a10038c24..866932eb5e5732aa5ae7c6f42cb160c4469b9c5d 100644
--- a/Source/wtf/HashMap.h
+++ b/Source/wtf/HashMap.h
@@ -376,7 +376,7 @@ namespace WTF {
         AddResult result = inlineAdd(key, mapped);
         if (!result.isNewEntry) {
             // The inlineAdd call above found an existing hash table entry; we need to set the mapped value.
-            MappedTraits::store(mapped, result.iterator->value);
+            MappedTraits::store(mapped, result.storedValue->value);
         }
         return result;
     }