The Special Characters language support causes errors loading plugins from 3.5 onwards

[Teresa Monahan]

The new support for translating the Special Characters plugin in CKEditor 3.5 causes errors when the editor is loading plugins. An example of this can be seen in the ui_languages sample in CKEditor 3.5, 3.5.1 and the nightly builds.

Steps to reproduce:

1. Open the ui_languages.html sample.
2. Open the Special Characters dialog.
3. Close the dialog by either inserting a character or clicking Cancel.
4. Change the language selected in the dropdown menu so that the editor is reloaded in a different language.

The following error occurs:

f.indexOf is not a function ​http://nightly.ckeditor.com/6405/ckeditor.js Line 9

The error occurs during the CKEDITOR.plugins.load() call in editor.js. This function calls CKEDITOR.tools.indexOf( pluginLangs, editor.langCode ) to try to set the language for the editor. However pluginLangs is a map, rather than an array and the indexOf call fails.

This is a high priority issue and we need to be able to patch it in CKEditor 3.5 and 3.5.1

[Sa'ar Zac Elias]

Dup of #7088.