Introduce Position constructor with const Node&

third_party/WebKit/Source/core/editing/PlainTextRange.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2005 Alexey Proskuryakov.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 166 matching lines @@
   Node* start_container = range.StartPosition().ComputeContainerNode();
   if (start_container != &scope && !start_container->IsDescendantOf(&scope))
     return PlainTextRange();
   Node* end_container = range.EndPosition().ComputeContainerNode();
   if (end_container != scope && !end_container->IsDescendantOf(&scope))
     return PlainTextRange();
 
   DocumentLifecycle::DisallowTransitionScope disallow_transition(
       scope.GetDocument().Lifecycle());
 
-  size_t start = TextIterator::RangeLength(
-      Position(&const_cast<ContainerNode&>(scope), 0), range.StartPosition());
-  size_t end = TextIterator::RangeLength(
-      Position(&const_cast<ContainerNode&>(scope), 0), range.EndPosition());
+  size_t start =
+      TextIterator::RangeLength(Position(scope, 0), range.StartPosition());
+  size_t end =
+      TextIterator::RangeLength(Position(scope, 0), range.EndPosition());
 
   return PlainTextRange(start, end);
 }
 
 PlainTextRange PlainTextRange::Create(const ContainerNode& scope,
                                       const Range& range) {
   return Create(scope, EphemeralRange(&range));
 }
 
 }  // namespace blink