Avoid unnecessary copies of AccessibilityChildrenVector

Source/modules/accessibility/AXObject.cpp

 /*
  * Copyright (C) 2008, 2009, 2011 Apple 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 517 matching lines @@
 {
     return isProgressIndicator()
         || isMeter()
         || isSlider()
         || isScrollbar()
         || isSpinButton();
 }
 
 void AXObject::ariaTreeRows(AccessibilityChildrenVector& result)
 {
-    AccessibilityChildrenVector axChildren = children();
+    const AccessibilityChildrenVector& axChildren = children();
     unsigned count = axChildren.size();
     for (unsigned k = 0; k < count; ++k) {
         AXObject* obj = axChildren[k].get();
 
         // Add tree items as the rows.
         if (obj->roleValue() == TreeItemRole)
             result.append(obj);
 
         // Now see if this item also has rows hiding inside of it.
         obj->ariaTreeRows(result);
@@ skipping 568 matching lines @@
 }
 
 const AtomicString& AXObject::roleName(AccessibilityRole role)
 {
     static const Vector<AtomicString>* roleNameVector = createRoleNameVector();
 
     return roleNameVector->at(role);
 }
 
 } // namespace blink