Use c++11 range loops in accessibility

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 c83c7e6d351ed229bb1d3d0f71ec96df34a9430f..5cfe41e969a18c0835b0c9e2577ea410c03b431b 100644
--- a/Source/modules/accessibility/AXTableColumn.cpp
+++ b/Source/modules/accessibility/AXTableColumn.cpp
@@ -79,10 +79,7 @@ void AXTableColumn::headerObjectsForColumn(AccessibilityChildrenVector& headers)
         return;
 
     if (toAXTable(m_parent)->isAriaTable()) {
-        const AccessibilityChildrenVector& columnChildren = children();
-        unsigned childrenCount = columnChildren.size();
-        for (unsigned i = 0; i < childrenCount; i++) {
-            AXObject* cell = columnChildren[i].get();
+        for (const auto& cell : children()) {
             if (cell->roleValue() == ColumnHeaderRole)
                 headers.append(cell);
         }