Make argument of slots explicit in examples

Make the name of arguments explicit by using the

onXXX: function(arg) {

syntax.

Change-Id: I1b24e444d4c8e2e26561edc043b53672ccb4de23
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: Michal Klocek <michal.klocek@qt.io>

src/webengine/api/qquickwebenginecontextmenurequest.cpp

@@ -80,7 +80,7 @@ ASSERT_ENUMS_MATCH(QtWebEngineCore::WebEngineContextMenuData::MediaTypePlugin,
     WebEngineView {
         id: view
         // ...
-        onContextMenuRequested: {
+        onContextMenuRequested: function(request) {
             request.accepted = true;
             myMenu.x = request.x;
             myMenu.y = request.y;

src/webengine/doc/src/webengineview.qdoc

@@ -1041,7 +1041,7 @@
     ApplicationWindow {
         id: window
         WebEngineView {
-            onFullScreenRequested: {
+            onFullScreenRequested: function(request) {
                 if (request.toggleOn)
                     window.showFullScreen()
                 else