[AX][GTK] Implement Text interface for document-web

https://bugs.webkit.org/show_bug.cgi?id=268154

Reviewed by NOBODY (OOPS!).

This patch changes slightly how the roles reported by the AT-SPI DOM
tree are available. The goal is to unify how browsers report roles on
their accessible trees. It makes WebKit mostly match what Firefox and
Chromium do.

It is based on three general rules discussed with Orca developers:

 1. Accessible objects that implements Text must also implement Hypertext
 2. Children of Hypertext implementors must implement Hyperlink
 3. The document-web object must implement Text

In practice, this makes all accessible objects under the document-web
object implement Hyperlink, and many more implement Text now.

* Source/WebCore/accessibility/atspi/AccessibilityObjectAtspi.cpp:
(WebCore::AccessibilityObjectAtspi::interfacesForObject):

Source/WebCore/accessibility/atspi/AccessibilityObjectAtspi.cpp

@@ -71,13 +71,10 @@ OptionSet<AccessibilityObjectAtspi::Interface> AccessibilityObjectAtspi::interfa
         interfaces.add(Interface::Text);
     else if (coreObject.isTextControl() || coreObject.isNonNativeTextControl())
         interfaces.add(Interface::Text);
-    else if (!coreObject.isWebArea()) {
-        if (coreObject.roleValue() != AccessibilityRole::Table) {
-            interfaces.add(Interface::Hypertext);
-            if ((renderer && renderer->childrenInline()) || roleIsTextType(coreObject.roleValue()) || coreObject.isMathToken())
-                interfaces.add(Interface::Text);
-        }
-    }
+    else if (coreObject.isWebArea())
+        interfaces.add(Interface::Text);
+    else if (coreObject.roleValue() != AccessibilityRole::Table && ((renderer && renderer->childrenInline()) || roleIsTextType(coreObject.roleValue()) || coreObject.isMathToken()))
+        interfaces.add(Interface::Text);
 
     if (coreObject.supportsRangeValue())
         interfaces.add(Interface::Value);
@@ -108,9 +105,19 @@ OptionSet<AccessibilityObjectAtspi::Interface> AccessibilityObjectAtspi::interfa
             interfaces.add(Interface::Image);
         else
             interfaces.add(Interface::Text);
-        interfaces.add(Interface::Hyperlink);
     }
 
+    // Anything that implements the Text interface should also implement the
+    // Hypertext interface
+    if (interfaces.contains(Interface::Text))
+        interfaces.add(Interface::Hypertext);
+
+    // All accessible objects beneath the web area should be linked by their
+    // parent. In practice, this means all objects except the root and the
+    // web area should be hyperlinks.
+    if (!coreObject.isWebArea() && coreObject.isDescendantOfRole(AccessibilityRole::WebArea))
+        interfaces.add(Interface::Hyperlink);
+
     return interfaces;
 }