Fix "checkWellKnownUrl" not being run

The check is run only if its last parameter is true; data() tries to
convert the HTML attribute string to an actual JavaScript value, so
"true" is returned as an actual boolean instead of an string; as a
strict comparison against "true" was used the result was false and thus
the checks were not run.

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>