Tracing: Fix runtime QML warnings

"QML Connections: Implicitly defined onFoo properties in Connections are
deprecated. Use this syntax instead: function onFoo(<arguments>)"

Change-Id: Idf65152f5aa1b96a739bd41f87893270b9da8e1b
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>

src/libs/tracing/qml/MainView.qml

@@ -51,12 +51,12 @@ Rectangle {
     // ***** connections with external objects
     Connections {
         target: zoomControl
-        onRangeChanged: {
+        function onRangeChanged() {
             zoomSliderToolBar.updateZoomLevel();
             content.scroll();
             selectionRange.update();
         }
-        onWindowChanged: {
+        function onWindowChanged() {
             content.scroll();
         }
     }