cubicweb #3524254 canvas tag doesn't survive html sanitizer [validation pending]

The iprogress cube uses such tags, and that content gets thrown out when using the rql rest directive with such a view.

prioritynormal
typebug
done in3.17.13
load0.100
load left0.000
closed by#c4581bc582e1 [uilib] allow canvas tags in the html cleaner
patch[uilib] allow canvas tags in the html cleaner [applied]