Make VisiblePosition::init to not use being constructed object

Source/core/editing/PositionWithAffinity.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file./*
 
 #include "config.h"
 #include "core/editing/PositionWithAffinity.h"
 
 namespace blink {
 
 template <typename PositionType>
 PositionWithAffinityTemplate<PositionType>::PositionWithAffinityTemplate(const PositionType& position, EAffinity affinity)
     : m_position(position)
     , m_affinity(affinity)
 {
 }
 
 template <typename PositionType>
 PositionWithAffinityTemplate<PositionType>::PositionWithAffinityTemplate()
     : m_affinity(DOWNSTREAM)
 {
 }
 
 template <typename PositionType>
 PositionWithAffinityTemplate<PositionType>::~PositionWithAffinityTemplate()
 {
 }
 
+template <typename PositionType>
+bool PositionWithAffinityTemplate<PositionType>::operator==(const PositionWithAffinityTemplate& other) const
+{
+    if (isNull())

[tkent, 2015/06/22 07:04:59]

Please document this in PositionWithAffinity.h.

[yosin_UTC9, 2015/06/22 07:25:35]

Done.

+        return other.isNull();
+    return m_affinity == other.m_affinity && m_position == other.m_position;
+}
+
 template class CORE_EXTERN_TEMPLATE_EXPORT PositionWithAffinityTemplate<Position>;
 
 } // namespace blink