Styles combo disabled when a style using multiple classes has them arranged in a non lexicographical order

[Tade0]

Steps to reproduce

1. Open: ​https://jsfiddle.net/feaxsLcL/
2. Click on the styles combo.

OR:

1. Create a minimal ckeditor instance that includes the stylescombo plugin and the styleSet configuration option set to:

[
  { name: 'Marker', element: 'span', attributes: { 'class': 'b-test a-test' } }
]

2. Click on the styles combo.

Expected result

Styles combo shows one style that's named "Marker".

Actual result

Styles combo is empty and disables itself upon clicking on it.

Other details (browser, OS, CKEditor version, installed plugins)

• With the class order switched the bug does not occur.

• The (bug-inducing) style is recognized but in this form the ACF filters it out from the styles list.

• Pasting this snippet:

<p><span class="b-test a-test">Test</span></p>

into the source and switching modes back and forth produces a sorted output like this:

<p><span class="a-test b-test">Test</span></p>

[Jakub Ś]

DUP of #13206