MDL-55183 editor_atto: Fix requires error.

When using a different theme and removing an editor
plugin such as the equation plugin, atto will display
an error about a missing dependency.

A thank you to Anthony Forth for providing this patch.

lib/editor/atto/yui/build/moodle-editor_atto-editor/moodle-editor_atto-editor-debug.js

@@ -2823,6 +2823,7 @@ Y.Base.mix(Y.M.editor_atto.Editor, [EditorFilepicker]);
         "event-simulate",
         "event-custom",
         "node-event-html5",
+        "node-event-simulate",
         "yui-throttle",
         "moodle-core-notification-dialogue",
         "moodle-core-notification-confirm",

lib/editor/atto/yui/build/moodle-editor_atto-editor/moodle-editor_atto-editor.js

@@ -2809,6 +2809,7 @@ Y.Base.mix(Y.M.editor_atto.Editor, [EditorFilepicker]);
         "event-simulate",
         "event-custom",
         "node-event-html5",
+        "node-event-simulate",
         "yui-throttle",
         "moodle-core-notification-dialogue",
         "moodle-core-notification-confirm",

lib/editor/atto/yui/src/editor/meta/editor.json

@@ -10,6 +10,7 @@
             "event-simulate",
             "event-custom",
             "node-event-html5",
+	    "node-event-simulate",
             "yui-throttle",
             "moodle-core-notification-dialogue",
             "moodle-core-notification-confirm",