Get rid of redundant layout tree update related to selection

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

Index: third_party/WebKit/Source/core/editing/DOMSelection.cpp
diff --git a/third_party/WebKit/Source/core/editing/DOMSelection.cpp b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
index 8d1a24704a2080ce07acdbb13d972dded6a10509..31cebb6047f19fdf825bdbf565fb01744276aa94 100644
--- a/third_party/WebKit/Source/core/editing/DOMSelection.cpp
+++ b/third_party/WebKit/Source/core/editing/DOMSelection.cpp
@@ -666,9 +666,7 @@ bool DOMSelection::containsNode(const Node* n, bool allowPartial) const {
   if (!isAvailable())
     return false;
 
-  FrameSelection& selection = frame()->selection();
-
-  if (frame()->document() != n->document() || selection.isNone())
+  if (frame()->document() != n->document())
     return false;
 
   unsigned nodeIndex = n->nodeIndex();
@@ -678,8 +676,11 @@ bool DOMSelection::containsNode(const Node* n, bool allowPartial) const {
   // |VisibleSelection::toNormalizedEphemeralRange| requires clean layout.
   frame()->document()->updateStyleAndLayoutIgnorePendingStylesheets();
 
+  FrameSelection& selection = frame()->selection();
   const EphemeralRange selectedRange =
       selection.selection().toNormalizedEphemeralRange();
+  if (selectedRange.isNull())
+    return false;
 
   ContainerNode* parentNode = n->parentNode();
   if (!parentNode)