[web/data] fix treeview regression (closes #3526466)
Changeset 68cde7431c2c "[js] remove 3.9 bw compat (where apparently
unused)" removed the use of form.callback from loadxhtml, which treeview
relied on. Update to add a callback on the loadxhtml return value
instead.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html