Implement aria properties setsize and posinset.

Source/modules/accessibility/AXObject.cpp

Index: Source/modules/accessibility/AXObject.cpp
diff --git a/Source/modules/accessibility/AXObject.cpp b/Source/modules/accessibility/AXObject.cpp
index 55c4a517c4e225c8aea22265ddab2e4bd875aa22..0db0c2e703539ec767c0989f9da312a0300fbd27 100644
--- a/Source/modules/accessibility/AXObject.cpp
+++ b/Source/modules/accessibility/AXObject.cpp
@@ -719,6 +719,25 @@ bool AXObject::supportsRangeValue() const
         || isSpinButton();
 }
 
+bool AXObject::supportsSetSizeAndPosInSet() const
+{
+    AXObject* parent = parentObject();
+    if (!parent)
+        return false;
+    int role = roleValue();
+    int parentRole = parent->roleValue();
+
+    if ((role == ListBoxOptionRole && parentRole == ListBoxRole)
+        || (role == ListItemRole && parentRole == ListRole)
+        || (role == MenuItemRole && parentRole == MenuRole)
+        || (role == RadioButtonRole && parentRole == RadioGroupRole)
+        || (role == TabRole && parentRole == TabListRole)
+        || (role == TreeItemRole && parentRole == TreeRole))
+        return true;
+
+    return false;
+}
+
 void AXObject::ariaTreeRows(AccessibilityChildrenVector& result)
 {
     for (const auto& child : children()) {