MDL-58182 javascript: Fix for buttons regression in core dialog.

Fixes a regression caused by MDL-56364, wherein the buttons were made
readOnly, meaning addButtons wouldn't work. This removes that change,
while maintaining the original dependency between the buttons and the
closeButton config options.

lib/yui/build/moodle-core-notification-dialogue/moodle-core-notification-dialogue-debug.js

@@ -72,6 +72,7 @@ DIALOGUE = function(config) {
               .append(Y.Node.create('<div class="' + CSS.FOOTER + ' yui3-widget-ft"></div>')));
     Y.one(document.body).append(config.notificationBase);
     config.srcNode = '#' + id;
+    delete config.buttons; // Don't let anyone pass in buttons as we want to control these during init. addButton can be used later.
     DIALOGUE.superclass.constructor.apply(this, [config]);
 };
 Y.extend(DIALOGUE, Y.Panel, {
@@ -778,9 +779,8 @@ Y.Base.modifyAttrs(DIALOGUE, {
      * @default {}
      */
     buttons: {
-        // Readonly is really important. We don't want to allow users of the plugin to pass in buttons. closeButton handles this.
-        readOnly: true,
         getter: Y.WidgetButtons.prototype._getButtons,
+        setter: Y.WidgetButtons.prototype._setButtons,
         valueFn: function() {
             if (this.get('closeButton') === false) {
                 return null;

lib/yui/build/moodle-core-notification-dialogue/moodle-core-notification-dialogue.js

@@ -72,6 +72,7 @@ DIALOGUE = function(config) {
               .append(Y.Node.create('<div class="' + CSS.FOOTER + ' yui3-widget-ft"></div>')));
     Y.one(document.body).append(config.notificationBase);
     config.srcNode = '#' + id;
+    delete config.buttons; // Don't let anyone pass in buttons as we want to control these during init. addButton can be used later.
     DIALOGUE.superclass.constructor.apply(this, [config]);
 };
 Y.extend(DIALOGUE, Y.Panel, {
@@ -775,9 +776,8 @@ Y.Base.modifyAttrs(DIALOGUE, {
      * @default {}
      */
     buttons: {
-        // Readonly is really important. We don't want to allow users of the plugin to pass in buttons. closeButton handles this.
-        readOnly: true,
         getter: Y.WidgetButtons.prototype._getButtons,
+        setter: Y.WidgetButtons.prototype._setButtons,
         valueFn: function() {
             if (this.get('closeButton') === false) {
                 return null;

lib/yui/src/notification/js/dialogue.js

@@ -42,6 +42,7 @@ DIALOGUE = function(config) {
               .append(Y.Node.create('<div class="' + CSS.FOOTER + ' yui3-widget-ft"></div>')));
     Y.one(document.body).append(config.notificationBase);
     config.srcNode = '#' + id;
+    delete config.buttons; // Don't let anyone pass in buttons as we want to control these during init. addButton can be used later.
     DIALOGUE.superclass.constructor.apply(this, [config]);
 };
 Y.extend(DIALOGUE, Y.Panel, {
@@ -748,9 +749,8 @@ Y.Base.modifyAttrs(DIALOGUE, {
      * @default {}
      */
     buttons: {
-        // Readonly is really important. We don't want to allow users of the plugin to pass in buttons. closeButton handles this.
-        readOnly: true,
         getter: Y.WidgetButtons.prototype._getButtons,
+        setter: Y.WidgetButtons.prototype._setButtons,
         valueFn: function() {
             if (this.get('closeButton') === false) {
                 return null;