Revert "QmlJsDebugger: Fix observer navigation on Mac OS X"

This reverts accidentally pushed commit 4f33fbc2.

share/qtcreator/qml/qmljsdebugger/qdeclarativeviewobserver.cpp

@@ -80,7 +80,6 @@ QDeclarativeViewObserver::QDeclarativeViewObserver(QDeclarativeView *view, QObje
     data->currentTool = data->selectionTool;
 
     data->view->setMouseTracking(true);
-    data->view->installEventFilter(this);
     data->view->viewport()->installEventFilter(this);
 
     data->debugService = QDeclarativeObserverService::instance();