modalDialog: Consistently return correct boolean for open() in ModalDialogs

Previously these calls either ignored the return from super.open() or
implicitely returned false.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2038>

js/ui/accessDialog.js

@@ -76,10 +76,12 @@ class AccessDialog extends ModalDialog.ModalDialog {
     }
 
     open() {
-        super.open();
+        if (!super.open())
+            return false;
 
         let connection = this._invocation.get_connection();
         this._requestExported = this._request.export(connection, this._handle);
+        return true;
     }
 
     CloseAsync(invocation, _params) {

js/ui/runDialog.js

@@ -249,8 +249,8 @@ class RunDialog extends ModalDialog.ModalDialog {
         this._commandError = false;
 
         if (this._lockdownSettings.get_boolean(DISABLE_COMMAND_LINE_KEY))
-            return;
+            return false;
 
-        super.open();
+        return super.open();
     }
 });

js/ui/welcomeDialog.js

@@ -26,9 +26,9 @@ class WelcomeDialog extends ModalDialog.ModalDialog {
 
     open() {
         if (!this._tourAppInfo)
-            return;
+            return false;
 
-        super.open();
+        return super.open();
     }
 
     _buildLayout() {