Get rid of redundant layout tree update related to selection

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

Index: third_party/WebKit/Source/core/editing/Editor.cpp
diff --git a/third_party/WebKit/Source/core/editing/Editor.cpp b/third_party/WebKit/Source/core/editing/Editor.cpp
index 4bf340fd5f88a108d11159655cef891e15700d7c..f1d55a9e975abd4ff82e61466288899c4970399c 100644
--- a/third_party/WebKit/Source/core/editing/Editor.cpp
+++ b/third_party/WebKit/Source/core/editing/Editor.cpp
@@ -1623,12 +1623,20 @@ void Editor::setMarkedTextMatchesAreHighlighted(bool flag) {
   frame().document()->markers().repaintMarkers(DocumentMarker::TextMatch);
 }
 
+SelectionType computeSelectionType(const SelectionInDOMTree& selection) {
+  if (selection.isNone())
+    return NoSelection;
+  if (selection.base() == selection.extent())
+    return CaretSelection;
+  return RangeSelection;
+}
+
 void Editor::respondToChangedSelection(
     const Position& oldSelectionStart,
     FrameSelection::SetSelectionOptions options) {
   spellChecker().respondToChangedSelection(oldSelectionStart, options);
-  client().respondToChangedSelection(&frame(),
-                                     frame().selection().getSelectionType());
+  client().respondToChangedSelection(
+      &frame(), computeSelectionType(frame().selection().selectionInDOMTree()));
   setStartNewKillRingSequence(true);
 }