Text control elements should contain all (shadow DOM) children.

third_party/WebKit/Source/core/layout/LayoutBox.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2005 Allan Sandfeld Jensen (kde@carewolf.com)
  *           (C) 2005, 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1964 matching lines @@
 }
 
 void LayoutBox::mapLocalToAncestor(const LayoutBoxModelObject* ancestor,
                                    TransformState& transformState,
                                    MapCoordinatesFlags mode) const {
   bool isFixedPos = style()->position() == EPosition::kFixed;
 
   // If this box has a transform or contains paint, it acts as a fixed position
   // container for fixed descendants, and may itself also be fixed position. So
   // propagate 'fixed' up only if this box is fixed position.
-  if (style()->canContainFixedPositionObjects() && !isFixedPos)
+  if (canContainFixedPositionObjects() && !isFixedPos)
     mode &= ~IsFixed;
   else if (isFixedPos)
     mode |= IsFixed;
 
   LayoutBoxModelObject::mapLocalToAncestor(ancestor, transformState, mode);
 }
 
 void LayoutBox::mapAncestorToLocal(const LayoutBoxModelObject* ancestor,
                                    TransformState& transformState,
                                    MapCoordinatesFlags mode) const {
   if (this == ancestor)
     return;
 
   bool isFixedPos = style()->position() == EPosition::kFixed;
 
   // If this box has a transform or contains paint, it acts as a fixed position
   // container for fixed descendants, and may itself also be fixed position. So
   // propagate 'fixed' up only if this box is fixed position.
-  if (style()->canContainFixedPositionObjects() && !isFixedPos)
+  if (canContainFixedPositionObjects() && !isFixedPos)
     mode &= ~IsFixed;
   else if (isFixedPos)
     mode |= IsFixed;
 
   LayoutBoxModelObject::mapAncestorToLocal(ancestor, transformState, mode);
 }
 
 LayoutSize LayoutBox::offsetFromContainer(const LayoutObject* o) const {
   ASSERT(o == container());
 
@@ skipping 3730 matching lines @@
 
 void LayoutBox::MutableForPainting::
     savePreviousContentBoxSizeAndLayoutOverflowRect() {
   auto& rareData = layoutBox().ensureRareData();
   rareData.m_hasPreviousContentBoxSizeAndLayoutOverflowRect = true;
   rareData.m_previousContentBoxSize = layoutBox().contentBoxRect().size();
   rareData.m_previousLayoutOverflowRect = layoutBox().layoutOverflowRect();
 }
 
 }  // namespace blink