Use minimal javascript expression for bound signals

Previously, QQmlBoundSignal used QQmlExpression internally.  This
commit adds a new, more optimal QQmlJavaScriptExpression subclass
specifically designed for QQmlBoundSignal, and converts the code
to use it instead of QQmlExpression where appropriate.

Task-number: QTBUG-24460
Change-Id: I2865a119ce840235e27a7722d8052ca61c265f69
Reviewed-by: Michael Brasser <michael.brasser@nokia.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/src/qml/qml/qqmlproperty_p.h b/src/qml/qml/qqmlproperty_p.h
index f4a9ced53b..e33c95ae41 100644
--- a/src/qml/qml/qqmlproperty_p.h
+++ b/src/qml/qml/qqmlproperty_p.h
@@ -64,7 +64,7 @@
 QT_BEGIN_NAMESPACE
 
 class QQmlContext;
-class QQmlExpression;
+class QQmlBoundSignalExpression;
 class QQmlEnginePrivate;
 class QQmlJavaScriptExpression;
 class Q_QML_PRIVATE_EXPORT QQmlPropertyPrivate : public QQmlRefCount
@@ -140,9 +140,9 @@ public:
     static QQmlAbstractBinding *setBinding(const QQmlProperty &that,
                                                    QQmlAbstractBinding *,
                                                    WriteFlags flags = DontRemoveBinding);
-    static QQmlExpression *signalExpression(const QQmlProperty &that);
-    static QQmlExpression *setSignalExpression(const QQmlProperty &that, 
-                                                       QQmlExpression *) ;
+    static QQmlBoundSignalExpression *signalExpression(const QQmlProperty &that);
+    static QQmlBoundSignalExpression *setSignalExpression(const QQmlProperty &that,
+                                                          QQmlBoundSignalExpression *) ;
     static bool write(const QQmlProperty &that, const QVariant &, WriteFlags);
     static bool writeBinding(QObject *, const QQmlPropertyData &,
                              QQmlContextData *context,