a11y: Add article and comment roles

Add new accessible roles
GTK_ACCESSIBLE_ROLE_ARTICLE and
GTK_ACCESSIBLE_ROLE_COMMENT.

ARIA has corresponding roles as well [1] [2],
with the article role being the superclass role
of the comment role.

Acccording to the ARIA spec, the article role
has the document role as superclass role and
the name can be set by the author.

For the comment role, the name can be set by the
author or come from the content.

The ARIA spec for the comment contains this sentence [2]:

> If the author has not explicitly declared aria-level, aria-posinset, or
> aria-setsize for a comment element, user agents MUST automatically
> compute the missing values and expose them to assistive technologies.

However, these properties are not listed as "Required States and
Properties" in the following table for that role. Potentially
the above requirement only applies for the first of the two
possible described cases of how the relationship between comments
and the commented content can be set, so don't hard-require
these attributes in the a11y overlay's
`check_widget_accessibility_errors` either.

[1] https://w3c.github.io/aria/#article
[2] https://w3c.github.io/aria/#comment

gtk/a11y/gtkatspiutils.c

@@ -48,6 +48,9 @@ gtk_accessible_role_to_atspi_role (GtkAccessibleRole role)
     case GTK_ACCESSIBLE_ROLE_APPLICATION:
       return ATSPI_ROLE_FRAME;
 
+    case GTK_ACCESSIBLE_ROLE_ARTICLE:
+      return ATSPI_ROLE_ARTICLE;
+
     case GTK_ACCESSIBLE_ROLE_BANNER:
       break;
 
@@ -75,6 +78,9 @@ gtk_accessible_role_to_atspi_role (GtkAccessibleRole role)
     case GTK_ACCESSIBLE_ROLE_COMMAND:
       break;
 
+    case GTK_ACCESSIBLE_ROLE_COMMENT:
+      return ATSPI_ROLE_COMMENT;
+
     case GTK_ACCESSIBLE_ROLE_COMPOSITE:
       break;
 

gtk/gtkaccessible.c

@@ -834,6 +834,8 @@ static const char *role_names[] = {
   [GTK_ACCESSIBLE_ROLE_APPLICATION] = NC_("accessibility", "application"),
   [GTK_ACCESSIBLE_ROLE_PARAGRAPH] = NC_("accessibility", "paragraph"),
   [GTK_ACCESSIBLE_ROLE_BLOCK_QUOTE] = NC_("accessibility", "block quote"),
+  [GTK_ACCESSIBLE_ROLE_ARTICLE] = NC_("accessibility", "article"),
+  [GTK_ACCESSIBLE_ROLE_COMMENT] = NC_("accessibility", "comment"),
 };
 
 /*< private >
@@ -950,6 +952,8 @@ static struct {
   { GTK_ACCESSIBLE_ROLE_ALERT, GTK_ACCESSIBLE_ROLE_ALERT_DIALOG },
   { GTK_ACCESSIBLE_ROLE_STATUS, GTK_ACCESSIBLE_ROLE_TIMER },
   { GTK_ACCESSIBLE_ROLE_DIALOG, GTK_ACCESSIBLE_ROLE_ALERT_DIALOG },
+  { GTK_ACCESSIBLE_ROLE_DOCUMENT, GTK_ACCESSIBLE_ROLE_ARTICLE },
+  { GTK_ACCESSIBLE_ROLE_ARTICLE, GTK_ACCESSIBLE_ROLE_COMMENT },
 };
 
 gboolean

gtk/gtkatcontext.c

@@ -1025,6 +1025,7 @@ gtk_at_context_get_accessible_relation (GtkATContext          *self,
 static guint8 naming[] = {
   [GTK_ACCESSIBLE_ROLE_ALERT] = NAME_FROM_AUTHOR,
   [GTK_ACCESSIBLE_ROLE_ALERT_DIALOG] = NAME_FROM_AUTHOR|GTK_ACCESSIBLE_NAME_REQUIRED,
+  [GTK_ACCESSIBLE_ROLE_ARTICLE] = NAME_FROM_AUTHOR,
   [GTK_ACCESSIBLE_ROLE_BANNER] = GTK_ACCESSIBLE_NAME_PROHIBITED,
   [GTK_ACCESSIBLE_ROLE_BLOCK_QUOTE] = NAME_FROM_AUTHOR,
   [GTK_ACCESSIBLE_ROLE_BUTTON] = NAME_FROM_AUTHOR|NAME_FROM_CONTENT|GTK_ACCESSIBLE_NAME_REQUIRED,
@@ -1034,6 +1035,7 @@ static guint8 naming[] = {
   [GTK_ACCESSIBLE_ROLE_COLUMN_HEADER] = NAME_FROM_AUTHOR|NAME_FROM_CONTENT|GTK_ACCESSIBLE_NAME_REQUIRED,
   [GTK_ACCESSIBLE_ROLE_COMBO_BOX] = NAME_FROM_AUTHOR|GTK_ACCESSIBLE_NAME_REQUIRED,
   [GTK_ACCESSIBLE_ROLE_COMMAND] = GTK_ACCESSIBLE_NAME_PROHIBITED,
+  [GTK_ACCESSIBLE_ROLE_COMMENT] = NAME_FROM_AUTHOR|NAME_FROM_CONTENT,
   [GTK_ACCESSIBLE_ROLE_COMPOSITE] = GTK_ACCESSIBLE_NAME_PROHIBITED,
   [GTK_ACCESSIBLE_ROLE_DIALOG] = NAME_FROM_AUTHOR|GTK_ACCESSIBLE_NAME_REQUIRED,
   [GTK_ACCESSIBLE_ROLE_DOCUMENT] = NAME_FROM_AUTHOR,

gtk/gtkenums.h

@@ -1367,6 +1367,12 @@ typedef enum {
  * @GTK_ACCESSIBLE_ROLE_BLOCK_QUOTE: A section of content that is quoted
  *   from another source.
  *   Since: 4.14
+ * @GTK_ACCESSIBLE_ROLE_ARTICLE: A section of a page that consists of a
+ *   composition that forms an independent part of a document, page, or site.
+ *   Since: 4.14
+ * @GTK_ACCESSIBLE_ROLE_COMMENT: A comment contains content expressing reaction
+ *   to other content.
+ *   Since: 4.14
  *
  * The accessible role for a [iface@Accessible] implementation.
  *
@@ -1455,7 +1461,9 @@ typedef enum {
   GTK_ACCESSIBLE_ROLE_TOGGLE_BUTTON GDK_AVAILABLE_ENUMERATOR_IN_4_10,
   GTK_ACCESSIBLE_ROLE_APPLICATION GDK_AVAILABLE_ENUMERATOR_IN_4_12,
   GTK_ACCESSIBLE_ROLE_PARAGRAPH GDK_AVAILABLE_ENUMERATOR_IN_4_14,
-  GTK_ACCESSIBLE_ROLE_BLOCK_QUOTE GDK_AVAILABLE_ENUMERATOR_IN_4_14
+  GTK_ACCESSIBLE_ROLE_BLOCK_QUOTE GDK_AVAILABLE_ENUMERATOR_IN_4_14,
+  GTK_ACCESSIBLE_ROLE_ARTICLE GDK_AVAILABLE_ENUMERATOR_IN_4_14,
+  GTK_ACCESSIBLE_ROLE_COMMENT GDK_AVAILABLE_ENUMERATOR_IN_4_14
 } GtkAccessibleRole;
 
 /**