Update some logic to check mixed state of ARIA elements.

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 27670088bcd2ffee9e9648b330f436ff832a6a89..d4d99c2affaec06beb3b5ba635a6332c91b0ebb0 100644
--- a/Source/modules/accessibility/AXObject.cpp
+++ b/Source/modules/accessibility/AXObject.cpp
@@ -377,8 +377,12 @@ AccessibilityButtonState AXObject::checkboxOrRadioValue() const
     const AtomicString& result = getAttribute(aria_checkedAttr);
     if (equalIgnoringCase(result, "true"))
         return ButtonStateOn;
-    if (equalIgnoringCase(result, "mixed"))
+    if (equalIgnoringCase(result, "mixed")) {
+        AccessibilityRole role = ariaRoleAttribute();
+        if (role == RadioButtonRole || role == MenuItemRadioRole)
+            return ButtonStateOff;
         return ButtonStateMixed;
+    }
 
     return ButtonStateOff;
 }