Fix initial window property values being propagated

This was broken since the the shell-surface refactoring.

Change-Id: I130b7396e85c570a9d11d609af6b3016e3f706f0
Reviewed-by: Dominik Holland <dominik.holland@pelagicore.com>
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

src/plugins/platforms/wayland/qwaylandwindow.cpp

@@ -176,6 +176,9 @@ void QWaylandWindow::initWindow()
                 mShellSurface->setAppId(appId);
             }
         }
+        // the user may have already set some window properties, so make sure to send them out
+        for (auto it = m_properties.cbegin(); it != m_properties.cend(); ++it)
+            mShellSurface->sendProperty(it.key(), it.value());
     }
 
     // Enable high-dpi rendering. Scale() returns the screen scale factor and will