wayland: don't allow maximization of applet popups

(cherry picked from commit 22e6b944)

src/xdgshellwindow.cpp

@@ -706,7 +706,7 @@ bool XdgToplevelWindow::isFullScreenable() const
 
 bool XdgToplevelWindow::isMaximizable() const
 {
-    if (!isResizable()) {
+    if (!isResizable() || isAppletPopup()) {
         return false;
     }
     if (rules()->checkMaximize(MaximizeRestore) != MaximizeRestore || rules()->checkMaximize(MaximizeFull) != MaximizeFull) {
@@ -1648,7 +1648,7 @@ void XdgToplevelWindow::changeMaximize(bool horizontal, bool vertical, bool adju
         return;
     }
 
-    if (!isResizable()) {
+    if (!isResizable() || isAppletPopup()) {
         return;
     }