QmlProfiler: Eliminate ambiguity from TimelineModelAggregator::count()

It wasn't helpful that this method could either count all events or
only the events from a specific model.

Change-Id: I09dcb37edd3403a23f6ee9008fc71b6761aa9e26
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

src/plugins/qmlprofiler/qml/Overview.qml

@@ -99,7 +99,10 @@ Canvas {
         target: qmlProfilerModelProxy
         onDataAvailable: {
             dataReady = true;
-            increment = Math.ceil(qmlProfilerModelProxy.count() / eventsPerPass);
+            increment = 0;
+            for (var i = 0; i < qmlProfilerModelProxy.modelCount(); ++i)
+                increment += qmlProfilerModelProxy.count(i);
+            increment = Math.ceil(increment / eventsPerPass);
             offset = -1;
             requestPaint();
         }