demobrowser: Fix meta object system warning

Do not redefine QWebEngineView::iconChanged.
This fixes the following warning:
QMetaObject::indexOfSignal: signal iconChanged(QIcon) from
QWebEngineView redefined in WebView

Change-Id: I2489bfcf9379200f9bfa24345b56679f138894fe
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

examples/webenginewidgets/demobrowser/webview.cpp

@@ -349,6 +349,7 @@ void WebView::setPage(WebPage *_page)
     connect(page(), SIGNAL(statusBarMessage(QString)),
             SLOT(setStatusBarText(QString)));
 #endif
+    disconnect(page(), &QWebEnginePage::iconChanged, this, &WebView::iconChanged);
     connect(page(), SIGNAL(iconChanged(QIcon)),
             this, SLOT(onIconChanged(QIcon)));
     connect(page(), &WebPage::featurePermissionRequested, this, &WebView::onFeaturePermissionRequested);

examples/webenginewidgets/demobrowser/webview.h

@@ -111,9 +111,6 @@ protected:
     void contextMenuEvent(QContextMenuEvent *event);
     void wheelEvent(QWheelEvent *event);
 
-signals:
-    void iconChanged(const QIcon &icon);
-
 private slots:
     void setProgress(int progress);
     void loadFinished(bool success);