IndexedDB: Return refs from a few const property accessors

Source/modules/indexeddb/IDBIndex.h

Index: Source/modules/indexeddb/IDBIndex.h
diff --git a/Source/modules/indexeddb/IDBIndex.h b/Source/modules/indexeddb/IDBIndex.h
index 6563f188cfcbd7d0495a27bda898a9a188fd6bc4..6557b51c1de9dee5573b3c60539797af50f2cf9d 100644
--- a/Source/modules/indexeddb/IDBIndex.h
+++ b/Source/modules/indexeddb/IDBIndex.h
@@ -51,10 +51,10 @@ public:
     ~IDBIndex();
 
     // Implement the IDL
-    const String name() const { return m_metadata.name; }
+    const String& name() const { return m_metadata.name; }
     PassRefPtr<IDBObjectStore> objectStore() const { return m_objectStore; }
     PassRefPtr<IDBAny> keyPathAny() const { return IDBAny::create(m_metadata.keyPath); }
-    const IDBKeyPath keyPath() const { return m_metadata.keyPath; }
+    const IDBKeyPath& keyPath() const { return m_metadata.keyPath; }
     bool unique() const { return m_metadata.unique; }
     bool multiEntry() const { return m_metadata.multiEntry; }
     int64_t id() const { return m_metadata.id; }