iOS: Don't re-apply window state during QIOSWindow construction

We set the parent of the window as part of constructing it, which will
cause a layout of the QIOSDesktopManagerView's subviews, but in this
case we don't need to re-set the window state as that's taken care of
later on in the QIOSWindow constructor.

Change-Id: Ic197c9a50394908c8aa2155abdc97bc322937a85
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@theqtcompany.com>
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>

src/plugins/platforms/ios/qiosviewcontroller.mm

@@ -75,7 +75,11 @@
 - (void)layoutView:(QUIView *)view
 {
     QWindow *window = view.qwindow;
-    Q_ASSERT(window->handle());
+
+    // Return early if the QIOSWindow is still constructing, as we'll
+    // take care of setting the correct window state in the constructor.
+    if (!window->handle())
+        return;
 
     // Re-apply window states to update geometry
     if (window->windowState() & (Qt::WindowFullScreen | Qt::WindowMaximized))