Table's columns and rows should not be modified outside.

Source/modules/accessibility/AXTable.cpp

Index: Source/modules/accessibility/AXTable.cpp
diff --git a/Source/modules/accessibility/AXTable.cpp b/Source/modules/accessibility/AXTable.cpp
index 78bb2cedf61b59dc275ed1b10b0452f4310bbe89..60d5f9ca6167252f32f5dadb61e0e561dc43dcc3 100644
--- a/Source/modules/accessibility/AXTable.cpp
+++ b/Source/modules/accessibility/AXTable.cpp
@@ -449,14 +449,14 @@ AXObject* AXTable::headerContainer()
     return m_headerContainer.get();
 }
 
-AXObject::AccessibilityChildrenVector& AXTable::columns()
+const AXObject::AccessibilityChildrenVector& AXTable::columns()
 {
     updateChildrenIfNecessary();
 
     return m_columns;
 }
 
-AXObject::AccessibilityChildrenVector& AXTable::rows()
+const AXObject::AccessibilityChildrenVector& AXTable::rows()
 {
     updateChildrenIfNecessary();