Fix a missing word in the docs

The functionality is "*no* longer available", of course.

Change-Id: I2c9f2633d74b98c16216f68e3d7e080422cf6506
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@digia.com>

src/quick/doc/src/appdevguide/porting.qdoc

@@ -190,7 +190,7 @@ new applications.)
 \section3 QDeclarativeItem and QDeclarativeView
 
 When porting to QQuickItem, note that QDeclarativeItem inherited from QGraphicsItem; in contrast,
-QQuickItem inherits directly from QObject, and any QGraphicsItem-specific functionality is longer
+QQuickItem inherits directly from QObject, and any QGraphicsItem-specific functionality is no longer
 available. In particular, QQuickItem does not have a \c paint() method for performing custom
 rendering through the QPainter API. Instead, in Qt 5, custom rendering should be performed through
 the new \c QSG* classes to take full advantage of the scene graph. See the \l {Qt Quick Scene Graph}