Enable selection for the composed tree

Source/core/layout/PendingSelection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 51 matching lines @@
     if (end.isNotNull() && (!end.inDocument() || end.document() != document))
         return false;
     PositionType extent = Strategy::selectionExtent(m_selection);
     if (extent.isNotNull() && (!extent.inDocument() || extent.document() != document))
         return false;
     return true;
 }
 
 bool PendingSelection::isInDocument(const Document& document) const
 {
+    if (RuntimeEnabledFeatures::selectionForComposedTreeEnabled())
+        return isInDocumentAlgorithm<VisibleSelection::InComposedTree>(document);
     return isInDocumentAlgorithm<VisibleSelection::InDOMTree>(document);
 }
 
 template <typename Strategy>
 VisibleSelection PendingSelection::calcVisibleSelectionAlgorithm() const
 {
     using PositionType = typename Strategy::PositionType;
 
     PositionType start = Strategy::selectionStart(m_selection);
     PositionType end = Strategy::selectionEnd(m_selection);
@@ skipping 13 matching lines @@
         VisiblePosition visibleExtent(end, affinity);
         visibleExtent = visibleExtent.next(CanSkipOverEditingBoundary);
         return VisibleSelection(visibleStart, visibleExtent);
     }
     VisiblePosition visibleEnd(end, selectionType == SelectionType::RangeSelection ? UPSTREAM : affinity);
     return VisibleSelection(visibleStart, visibleEnd);
 }
 
 VisibleSelection PendingSelection::calcVisibleSelection() const
 {
+    if (RuntimeEnabledFeatures::selectionForComposedTreeEnabled())
+        return calcVisibleSelectionAlgorithm<VisibleSelection::InComposedTree>();
     return calcVisibleSelectionAlgorithm<VisibleSelection::InDOMTree>();
 }
 
 DEFINE_TRACE(PendingSelection)
 {
     visitor->trace(m_selection);
 }
 
 } // namespace blink