Fix memory leak in QV4::QQmlSequence

Use the correct destructor in QV4::QQmlSequence::destroy() to prevent
memory leak

Change-Id: If9531f731abe5cd9aecfb9642ebf4f5108978f99
Reviewed-by: Simon Hausmann <simon.hausmann@digia.com>

src/qml/jsruntime/qv4sequenceobject.cpp

@@ -507,7 +507,7 @@ private:
 
     static void destroy(Managed *that)
     {
-        static_cast<QQmlSequence<Container> *>(that)->~QQmlSequence<Container>();
+        static_cast<QQmlSequence<Container> *>(that)->d()->~Data();
     }
 };