Get rid of redundant layout tree update related to selection

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

Index: third_party/WebKit/Source/core/editing/SelectionTemplate.cpp
diff --git a/third_party/WebKit/Source/core/editing/SelectionTemplate.cpp b/third_party/WebKit/Source/core/editing/SelectionTemplate.cpp
index 36ef7ba5f453f83aaa81dd24b6dd88b566c9aaa0..e987bb4f0fe24b8948781ecad886c7d5d615757a 100644
--- a/third_party/WebKit/Source/core/editing/SelectionTemplate.cpp
+++ b/third_party/WebKit/Source/core/editing/SelectionTemplate.cpp
@@ -133,6 +133,22 @@ void SelectionTemplate<Strategy>::showTreeForThis() const {
 #endif
 
 template <typename Strategy>
+const PositionTemplate<Strategy>&
+SelectionTemplate<Strategy>::computeEndPosition() const {

[yoichio, 2017/02/17 02:26:11]

Could you rename just endPosition because
 this function doesn't consume much computing.

[yosin_UTC9, 2017/02/17 05:14:49]

No, compute{Start,End}Position() compares positions, comparing positions takes
time.

+  if (m_base == m_extent)
+    return m_base;
+  return m_base < m_extent ? m_extent : m_base;
+}
+
+template <typename Strategy>
+const PositionTemplate<Strategy>&
+SelectionTemplate<Strategy>::computeStartPosition() const {

[yoichio, 2017/02/17 02:26:11]

ditto

[yosin_UTC9, 2017/02/17 05:14:49]

computeStartPosition() isn't cheap due by comparing positions.

+  if (m_base == m_extent)
+    return m_base;
+  return m_base < m_extent ? m_base : m_extent;
+}
+
+template <typename Strategy>
 void SelectionTemplate<Strategy>::printTo(std::ostream* ostream,
                                           const char* type) const {
   if (isNone()) {