Make Position::BeforeNode() to take const Node& instead of Node*

third_party/WebKit/Source/core/editing/Position.h

 /*
  * Copyright (C) 2004, 2006, 2008 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 49 matching lines @@
   PositionTemplate()
       : offset_(0), anchor_type_(PositionAnchorType::kOffsetInAnchor) {}
 
   static const TreeScope* CommonAncestorTreeScope(
       const PositionTemplate<Strategy>&,
       const PositionTemplate<Strategy>& b);
   static PositionTemplate<Strategy> EditingPositionOf(Node* anchor_node,
                                                       int offset);
 
   // For creating before/after positions:
-  PositionTemplate(Node* anchor_node, PositionAnchorType);
+  PositionTemplate(const Node* anchor_node, PositionAnchorType);
 
   // For creating offset positions:
   PositionTemplate(const Node& anchor_node, int offset);
   // TODO(editing-dev): We should not pass |nullptr| as |anchor_node| for
   // |Position| constructor.
   // TODO(editing-dev): This constructor should eventually go away. See bug
   // http://wkb.ug/63040.
   PositionTemplate(const Node* anchor_node, int offset);
 
   PositionTemplate(const PositionTemplate&);
@@ skipping 100 matching lines @@
 
   // These can be either inside or just before/after the node, depending on
   // if the node is ignored by editing or not.
   // FIXME: These should go away. They only make sense for legacy positions.
   bool AtFirstEditingPositionForNode() const;
   bool AtLastEditingPositionForNode() const;
 
   bool AtStartOfTree() const;
   bool AtEndOfTree() const;
 
-  static PositionTemplate<Strategy> BeforeNode(Node* anchor_node);
+  static PositionTemplate<Strategy> BeforeNode(const Node& anchor_node);
   static PositionTemplate<Strategy> AfterNode(Node* anchor_node);
   static PositionTemplate<Strategy> InParentBeforeNode(const Node& anchor_node);
   static PositionTemplate<Strategy> InParentAfterNode(const Node& anchor_node);
   static int LastOffsetInNode(Node* anchor_node);
   static PositionTemplate<Strategy> FirstPositionInNode(Node* anchor_node);
   static PositionTemplate<Strategy> LastPositionInNode(Node* anchor_node);
   static PositionTemplate<Strategy> FirstPositionInOrBeforeNode(
       Node* anchor_node);
   static PositionTemplate<Strategy> LastPositionInOrAfterNode(
       Node* anchor_node);
@@ skipping 81 matching lines @@
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 void showTree(const blink::Position&);
 void showTree(const blink::Position*);
 #endif
 
 #endif  // Position_h