This filter allows developers to modify the data that is used to create tag
clouds, without having to manipulate the tag cloud markup directly.
As part of the refactor, this changeset also adds a few unit tests for the way
`wp_generate_tag_cloud()` generates the 'title' attribute, as well as
improvements to output escaping.
Props flixos90, ysalame.
Fixes#24656.
git-svn-id: https://develop.svn.wordpress.org/trunk@32996 602fd350-edb4-49c9-b593-d223f7449a82
10d81a3fe5