cubicweb #5377672 [IE9] "cubicweb:target" attribute on `<form>` causes troubles on IE [validation pending]

The "cubicweb:target" attribute was introduced when CW used "xhtml" doctype. But now CW use the "html" doctype.

With the "html" doctype, when IE9 sees "cubicweb:target" attribute, it seems that it does not post the form inside the iframe.

priorityimportant
typebug
done in3.19.12
load2.000
load left0.000
closed by#62e138b915bb [web/views/formrenderer] remove `cubicweb:target` attribute on form once the target <iframe> is inserted
patch[web/views/formrenderer] do not use `cubicweb:target` attribute on form (closes #5377672) [applied][web/views/formrenderer] remove `cubicweb:target` attribute on form once the target <iframe> is inserted [applied]