Don't store data as a property on WP_Term objects.

`wp_ajax_add_term()` fetches a term using `get_term()`, and passes the term to
`WP_Ajax_Response`, which expects each of the term's properties to be scalar.
Having `$data` as a `stdClass` (meant to mimic `WP_User::data`, populated by
a `get_row()` database query) violated this expectation, causing fatal string
conversion errors. As a workaround, `$term->data` is converted so that it is
no longer an actual property of the term object, but is assembled only when
requested in the magic `__get()` method.

Fixes #34348.
Built from https://develop.svn.wordpress.org/trunk@35269


git-svn-id: http://core.svn.wordpress.org/trunk@35235 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-alpha-35268';
+$wp_version = '4.4-alpha-35269';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.