cubicweb #2869456 fix/enhance page validation in test [validation pending]

3.17 introduce breaking of several test: the HTMLValidator, which is now used by default, choke on e.g. canvas element. Also, the DTDValidator isn't used in case where it could.

We should:

  • use a validator that check XML well-formness only by default (html5 doctype)
  • use DTD validator if another doctype is specified
  • else use the HTMLValidator
prioritynormal
typebug
done in3.17.1
load0.500
load left0.000
closed by#269548f2306e [testlib] fix page validator selection. Closes #2869456
patch[testlib] fix page validator selection. Closes #2869456 [applied][testlib] fix page validator selection. Closes #2869456 [applied]