MDL-76562 editor_tiny: Added functions to remove button/menu/submenu.

Added a few functions to remove the toolbar button, menubar and sub-menu items.
One of the implementations is to remove the justify alignment in the toolbar and
the sub-menu items to aid the accessibility aspect of the TinyMCE editor.

lib/editor/tiny/amd/src/editor.js

@@ -26,7 +26,8 @@ import Pending from 'core/pending';
 import {getDefaultConfiguration} from './defaults';
 import {getTinyMCE, baseUrl} from './loader';
 import * as Options from './options';
-import {addToolbarButton, addToolbarButtons, addToolbarSection} from './utils';
+import {addToolbarButton, addToolbarButtons, addToolbarSection,
+    removeToolbarButton, removeSubmenuItem} from './utils';
 
 /**
  * Storage for the TinyMCE instances on the page.
@@ -245,6 +246,11 @@ const getStandardConfig = (target, tinyMCE, options, plugins) => {
 
         setup: (editor) => {
             Options.register(editor, options);
+
+            editor.on('init', function() {
+                // Hide justify alignment sub-menu.
+                removeSubmenuItem(editor, 'align', 'tiny:justify');
+            });
         },
     });
 
@@ -255,6 +261,9 @@ const getStandardConfig = (target, tinyMCE, options, plugins) => {
     config.toolbar = addToolbarSection(config.toolbar, 'directionality', 'alignment', true);
     config.toolbar = addToolbarButtons(config.toolbar, 'directionality', ['ltr', 'rtl']);
 
+    // Remove the align justify button from the toolbar.
+    config.toolbar = removeToolbarButton(config.toolbar, 'alignment', 'alignjustify');
+
     return config;
 };