Revert of Add documentation to 2 DeprecatedPaintLayer objects

Source/core/paint/DeprecatedPaintLayerStackingNodeIterator.h

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 20 matching lines @@
 #ifndef DeprecatedPaintLayerStackingNodeIterator_h
 #define DeprecatedPaintLayerStackingNodeIterator_h
 
 #include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 
 namespace blink {
 
 enum ChildrenIteration {
     NegativeZOrderChildren = 1,
-    // Normal flow children are not mandated by CSS 2.1 but are an artifact of
-    // our implementation: we allocate DeprecatedPaintLayers for elements that
-    // are not treated as stacking contexts and thus we need to walk them
-    // during painting and hit-testing.
     NormalFlowChildren = 1 << 1,
     PositiveZOrderChildren = 1 << 2,
     AllChildren = NegativeZOrderChildren | NormalFlowChildren | PositiveZOrderChildren
 };
 
 class DeprecatedPaintLayerStackingNode;
 class DeprecatedPaintLayer;
 
 // This iterator walks the DeprecatedPaintLayerStackingNode lists in the following order:
 // NegativeZOrderChildren -> NormalFlowChildren -> PositiveZOrderChildren.
@@ skipping 32 matching lines @@
 
     const DeprecatedPaintLayerStackingNode& m_root;
     unsigned m_remainingChildren;
     int m_index;
     DeprecatedPaintLayer* m_currentNormalFlowChild;
 };
 
 } // namespace blink
 
 #endif // DeprecatedPaintLayerStackingNodeIterator_h