WP_Term_Query does not return all terms when 'number' and 'object_ids' are specified

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When querying for taxonomy terms assigned to certain objects, WP_Term_Query's query is LIMIT'ed if the 'number' argument is specified. This introduces a problem similar to hierarchical taxonomies where results must not be limited in order to retrieve children. In particular, the issue arises because each term_taxonomy_id, or "(term, taxonomy) couple", has more than one relationship in wp_term_relationships thus more than 1 row could be returned for the same term_taxonomy_id.

It is worth to notice that in order to replicate the problem in the attached test, the 'order' argument must be set to DESC which is the opposite of WP_Term_Query's default.

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PHPUnit test

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Patch