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

Source/platform/network/ResourceResponse.cpp

Index: Source/platform/network/ResourceResponse.cpp
diff --git a/Source/platform/network/ResourceResponse.cpp b/Source/platform/network/ResourceResponse.cpp
index 0b156692cd0ce2b3244fb4bbcb55f31821115fe9..ea22e78ea2851a5411cf9de280c0cf29376ea646 100644
--- a/Source/platform/network/ResourceResponse.cpp
+++ b/Source/platform/network/ResourceResponse.cpp
@@ -311,7 +311,7 @@ void ResourceResponse::addHTTPHeaderField(const AtomicString& name, const Atomic
 
     HTTPHeaderMap::AddResult result = m_httpHeaderFields.add(name, value);
     if (!result.isNewEntry)
-        result.iterator->value = result.iterator->value + ", " + value;
+        result.storedValue->value = result.storedValue->value + ", " + value;
 }
 
 void ResourceResponse::clearHTTPHeaderField(const AtomicString& name)