Avoid unnecessary copies of AccessibilityChildrenVector

Source/modules/accessibility/AXTableColumn.cpp

Index: Source/modules/accessibility/AXTableColumn.cpp
diff --git a/Source/modules/accessibility/AXTableColumn.cpp b/Source/modules/accessibility/AXTableColumn.cpp
index 6622571475fbe5a6b3d862cfcd0214150f6ed296..7b9b9ad3e9ac7427467dc3c43b18eeff1559b5c2 100644
--- a/Source/modules/accessibility/AXTableColumn.cpp
+++ b/Source/modules/accessibility/AXTableColumn.cpp
@@ -79,7 +79,7 @@ void AXTableColumn::headerObjectsForColumn(AccessibilityChildrenVector& headers)
         return;
 
     if (toAXTable(m_parent)->isAriaTable()) {
-        AccessibilityChildrenVector columnChildren = children();
+        const AccessibilityChildrenVector& columnChildren = children();
         unsigned childrenCount = columnChildren.size();
         for (unsigned i = 0; i < childrenCount; i++) {
             AXObject* cell = columnChildren[i].get();