tiny mce icon description missing

I have got the same issue I think. The tooltip shows “post_snippets.desc” which is not a disaster but not very descriptive. I am using Version 2.3.5 on WordPress 4.2.2. I am not using any language translation.

The problem seems to be the title in editor_plugin.js:

// Register example button
			ed.addButton('post_snippets', {
				title : 'post_snippets.desc',
				cmd : 'mce_post_snippets',
				image : url + '/post-snippets.gif'
			});