Utilize Position::IsEquivalent() in {Up,Down}streamIgnoringEditingBoundaries()

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

Index: third_party/WebKit/Source/core/editing/Position.cpp
diff --git a/third_party/WebKit/Source/core/editing/Position.cpp b/third_party/WebKit/Source/core/editing/Position.cpp
index 0e2032eccc2815a65af2e58c08ac5c9e8613fefd..eab61e4ba6df3f245d5175760b3664b13d1dca26 100644
--- a/third_party/WebKit/Source/core/editing/Position.cpp
+++ b/third_party/WebKit/Source/core/editing/Position.cpp
@@ -355,6 +355,8 @@ bool PositionTemplate<Strategy>::operator>=(
 template <typename Strategy>
 bool PositionTemplate<Strategy>::IsEquivalent(
     const PositionTemplate<Strategy>& other) const {
+  if (IsNull())

[Xiaocheng, 2017/05/12 18:00:05]

This should go to the previous patch.

[yoichio, 2017/05/15 01:41:53]

I oppose this change from the math sense.
For example, Nan should not equal any number including
 Nan itself.
How about |while(position.IsValid() && position != lastposition)|
  in the caller? 

[yosin_UTC9, 2017/05/15 05:12:57]

Oops, I missed rebasing.
Talked offline.

In this patch, we use Position::IsEqualivalent() as replacement of operator==()
to
minimize patch size.

We'll get rid of null-Position usage in future.

+    return other.IsNull();
   if (anchor_type_ == other.anchor_type_)
     return *this == other;
   return ToOffsetInAnchor() == other.ToOffsetInAnchor();