This is a workaround for an upstream bug which I have not been able to
reproduce outside of Moodle whereby the editor.contentWindow does not
match the editor.iframeElement.contentWindow when it should.
This issue only seems to affect Firefox, and it may even be a bug in
Firefox. It can only be reproduced when using a fresh browser which has
never had a TinyMCE window open.
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.
Part of MDL-75966
This commit adds TinyMCE version 6.1 into Moodle core.
A basic editor implementation is included, along with Moodle loader, and
basic Plugin API for Moodle. The Plugin API will be extended and
improved in future changes.
A new subplugin is defined for this plugin.
