Fixed perf regression by removing tree traversal for text sibling.

third_party/WebKit/Source/core/dom/Element.cpp

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index 469bc7a952c742e9449d340a4b81df0a039a8166..c78ef3cae1563bb80a6aed761b58502d9a8dad73 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1836,7 +1836,7 @@ PassRefPtr<ComputedStyle> Element::originalStyleForLayoutObject() {
   return document().ensureStyleResolver().styleForElement(this);
 }
 
-void Element::recalcStyle(StyleRecalcChange change) {
+void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
   DCHECK(document().inStyleRecalc());
   DCHECK(!document().lifecycle().inDetach());
   DCHECK(!parentOrShadowHostNode()->needsStyleRecalc());
@@ -1857,7 +1857,7 @@ void Element::recalcStyle(StyleRecalcChange change) {
       }
     }
     if (parentComputedStyle())
-      change = recalcOwnStyle(change);
+      change = recalcOwnStyle(change, nextTextSibling);
     clearNeedsStyleRecalc();
     clearNeedsReattachLayoutTree();
   }
@@ -1918,7 +1918,8 @@ PassRefPtr<ComputedStyle> Element::propagateInheritedProperties(
   return newStyle;
 }
 
-StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change) {
+StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
+                                          Text* nextTextSibling) {
   DCHECK(document().inStyleRecalc());
   DCHECK(!parentOrShadowHostNode()->needsStyleRecalc());
   DCHECK(change >= IndependentInherit || needsStyleRecalc());
@@ -1943,7 +1944,8 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change) {
   }
 
   if (localChange == Reattach) {
-    document().addNonAttachedStyle(*this, std::move(newStyle));
+    document().addStyleRecalcData(
+        *this, new StyleRecalcData(std::move(newStyle), nextTextSibling));
     setNeedsReattachLayoutTree();
     return rebuildLayoutTree();
   }
@@ -1989,8 +1991,9 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change) {
 
 StyleRecalcChange Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
+  StyleRecalcData* styleRecalcData = document().getStyleRecalcData(*this);
   AttachContext reattachContext;
-  reattachContext.resolvedStyle = document().getNonAttachedStyle(*this);
+  reattachContext.resolvedStyle = styleRecalcData->computedStyle.get();
   bool layoutObjectWillChange = needsAttach() || layoutObject();
 
   // We are calling Element::rebuildLayoutTree() from inside
@@ -2010,7 +2013,7 @@ StyleRecalcChange Element::rebuildLayoutTree() {
     // we can either traverse the current subtree from this node onwards
     // or store it.
     // The choice is between increased time and increased memory complexity.
-    reattachWhitespaceSiblingsIfNeeded(nextTextSibling());
+    reattachWhitespaceSiblingsIfNeeded(styleRecalcData->nextTextSibling);
     return Reattach;
   }
   return ReattachNoLayoutObject;