Use VisibleSelection::InDOMTree::equalSelections() instead of operator==()

Source/core/editing/VisibleSelection.cpp

 /*
  * Copyright (C) 2004, 2005, 2006 Apple Computer, 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 1137 matching lines @@
 }
 
 void VisibleSelection::validatePositionsIfNeeded()
 {
     if (!isValidPosition(m_base) || !isValidPosition(m_extent) || !isValidPosition(m_start) || !isValidPosition(m_end))
         validate();
 }
 
 bool VisibleSelection::InDOMTree::equalSelections(const VisibleSelection& selection1, const VisibleSelection& selection2)
 {
-    return selection1 == selection2;
+    if (selection1.affinity() != selection2.affinity() || selection1.isDirectional() != selection2.isDirectional())

[hajimehoshi, 2015/06/24 06:48:45]

Why is this needed? This seems redundant. The composed tree version doesn't have
this.

[yosin_UTC9, 2015/06/24 07:02:52]

I just copied from original code.

It seems we need to have this. :-<

Below link describes the reason of this code:
https://codereview.chromium.org/1089283002#msg14

+        return false;
+
+    if (selection1.isNone())

[hajimehoshi, 2015/06/24 06:48:45]

This could also be redundant, but I'm not sure. What do you think?

[yosin_UTC9, 2015/06/24 07:02:52]

I just copied from original code.
If we should remove them, we should have another patch.

This code avoids to call |Position::operator==()| on null case.

+        return selection2.isNone();
+
+    return selection1.start() == selection2.start() && selection1.end() == selection2.end() && selection1.affinity() == selection2.affinity()
+        && selection1.isDirectional() == selection2.isDirectional() && selection1.base() == selection2.base() && selection1.extent() == selection2.extent();
 }
 
 bool VisibleSelection::InComposedTree::equalSelections(const VisibleSelection& a, const VisibleSelection& b)
 {
     return a.startInComposedTree() == b.startInComposedTree() && a.endInComposedTree() == b.endInComposedTree() && a.affinity() == b.affinity() && a.isBaseFirst() == b.isBaseFirst() && a.isDirectional() == b.isDirectional();
 }
 
 #ifndef NDEBUG
 
 void VisibleSelection::debugPosition(const char* message) const
@@ skipping 71 matching lines @@
     sel.showTreeForThis();
 }
 
 void showTree(const blink::VisibleSelection* sel)
 {
     if (sel)
         sel->showTreeForThis();
 }
 
 #endif