Aria-details takes an ID reference, not an ID reference list

third_party/WebKit/public/web/WebAXEnums.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 361 matching lines @@
 enum class WebAXStringAttribute {
   kAriaKeyShortcuts,
   kAriaRoleDescription,
 };
 
 // Sparse attributes of a WebAXObject whose value is a reference to
 // another WebAXObject within the same frame. In order for it to be a
 // sparse attribute the default value must be the null WebAXObject.
 enum class WebAXObjectAttribute {
   kAriaActiveDescendant,
+  kAriaDetails,
   kAriaErrorMessage,
 };
 
 // Sparse attributes of a WebAXObject whose value is a vector of
 // references to other WebAXObjects within the same frame. In order
 // for it to be a sparse attribute the default value must be the
 // empty vector.
 enum class WebAXObjectVectorAttribute {
   kAriaControls,
-  kAriaDetails,
   kAriaFlowTo,
 };
 
 }  // namespace blink
 
 #endif