Fix null ptr exception

third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp

 /*
  * Copyright (C) 2012, 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 525 matching lines @@
   }
 
   if (isHTMLSelectElement(*GetNode())) {
     HTMLSelectElement& select_element = toHTMLSelectElement(*GetNode());
     return select_element.IsMultiple() ? kListBoxRole : kPopUpButtonRole;
   }
 
   if (isHTMLOptionElement(*GetNode())) {
     HTMLSelectElement* select_element =
         toHTMLOptionElement(GetNode())->OwnerSelectElement();
-    return select_element->IsMultiple() ? kListBoxOptionRole
-                                        : kMenuListOptionRole;
+    return !select_element || select_element->IsMultiple()
+               ? kListBoxOptionRole
+               : kMenuListOptionRole;
   }
 
   if (isHTMLTextAreaElement(*GetNode()))
     return kTextFieldRole;
 
   if (HeadingLevel())
     return kHeadingRole;
 
   if (isHTMLDivElement(*GetNode()))
     return kGenericContainerRole;
@@ skipping 2674 matching lines @@
     return String();
   return ToTextControlElement(node)->StrippedPlaceholder();
 }
 
 DEFINE_TRACE(AXNodeObject) {
   visitor->Trace(node_);
   AXObjectImpl::Trace(visitor);
 }
 
 }  // namespace blink