Algorithm for deciding which cells handle sorting is exactly
the same as in the real jQuery Tablesorter.
Depends on changes in VE core:
* I50426e173c68af7df49e47fe3bec0465a9a55c26
* Iabb372dfe7bf5feef314315ac74a788c6c58dc20
Bug: T139072
Change-Id: I4446be2ad459b05590754da9bb6c3dd8f796be42
The DM side already had the mixin, the CE side was still using custom
logic that has since been moved to ce.ClassAttributeNode.
This fixes the issue of tables not getting the wikitable class in VE
as it was only applied on attribute change previously, which never happened.
Change-Id: I197347762fc9228034f7664484539e5888722bcf
