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

Source/core/editing/VisibleSelection.cpp

Index: Source/core/editing/VisibleSelection.cpp
diff --git a/Source/core/editing/VisibleSelection.cpp b/Source/core/editing/VisibleSelection.cpp
index 0b39efb9a635dfa0b11f3d2b5143a10a0a25a017..814ddef302fb56e0251dd663d876fb10d8e417ac 100644
--- a/Source/core/editing/VisibleSelection.cpp
+++ b/Source/core/editing/VisibleSelection.cpp
@@ -1155,7 +1155,14 @@ void VisibleSelection::validatePositionsIfNeeded()
 
 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)