Improve handling of dictionary conversions.

Source/core/storage/StorageEvent.h

Index: Source/core/storage/StorageEvent.h
diff --git a/Source/core/storage/StorageEvent.h b/Source/core/storage/StorageEvent.h
index 958063229d963f003473986f604613e5ce62f677..2e6743a79d17e3009122d08437dfb08a844c25a3 100644
--- a/Source/core/storage/StorageEvent.h
+++ b/Source/core/storage/StorageEvent.h
@@ -55,6 +55,7 @@ public:
     const String& newValue() const { return m_newValue; }
     const String& url() const { return m_url; }
     Storage* storageArea() const { return m_storageArea.get(); }
+    Storage* storageArea(bool& isNull) const { isNull = !m_storageArea; return m_storageArea.get(); }
 
     void initStorageEvent(const AtomicString& type, bool canBubble, bool cancelable, const String& key, const String& oldValue, const String& newValue, const String& url, Storage* storageArea);