This change causes explicit role=none and role=presentation attribute
values to be ignored in cases where the elements for which those values
are specified are either focusable, or have global ARIA attributes —
per https://w3c.github.io/aria/#conflict_resolution_presentation_none.
This change implements the role-checking requirement from the ARIA spec
at https://w3c.github.io/aria/#document-handling_author-errors_roles
that the “form” and “region” roles are required to have accessible
names — and that if they don’t have accessible names as required, UAs
must treat them as if they’d not been specified at all.
This change causes explicitly-specified role attributes to be ignored in
the case where the specified role is “orphaned” — that is, when its
element lacks a required ancestor with an appropriate role.
This change adds a virtual to_element function to ARIAMixin, and
overrides it in DOM::Element so it can then be used back inside
ARIAMixin to get an element when needed (for example, when computing a
role requires checking the roles of ancestors of an element).
This change does replacement of ARIA roles that have newer synonyms.
There are a number of newer ARIA roles that are synonyms for older
roles. https://wpt.fyi/results/wai-aria/role/synonym-roles.html has a
number of subtests which expect that when retrieving the value of an
explicitly- specified role attribute, if the value is one of the older
role values, implementations must replace that with its newer synonym.
This change separates the steps for checking the string value of the
ARIA “role” attribute out from the element.role_or_default() function
into a separate function — in order to expose a way to just check if the
ARIA “role” attribute actually has a value, without also then computing
a default role value if no “role” attribute value was found.
Otherwise, without this change, the only available function for
retrieving ARIA role values is the element.role_or_default() function —
which always does the additional step of computing (and returning) a
default role value if no “role” attribute is found.
