Remove calls to styleForLayoutObject() in LayoutTreeBuilder::style()

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc.
  * All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
@@ skipping 2002 matching lines @@
 
   StyleRecalcChange localChange =
       ComputedStyle::stylePropagationDiff(oldStyle.get(), newStyle.get());
   if (localChange == NoChange) {
     INCREMENT_STYLE_STATS_COUNTER(document().styleEngine(), stylesUnchanged, 1);
   } else {
     INCREMENT_STYLE_STATS_COUNTER(document().styleEngine(), stylesChanged, 1);
   }
 
   if (localChange == Reattach) {
+    // This mimicks Element::recalcStyleForLayout except it also stores the
+    // nextTextSibling information and sets the NeedsReattachLayoutTree flag.
     StyleReattachData styleReattachData;
     styleReattachData.computedStyle = std::move(newStyle);
     styleReattachData.nextTextSibling = nextTextSibling;
     document().addStyleReattachData(*this, styleReattachData);
     setNeedsReattachLayoutTree();
+    recalcShadowRootStylesForLayout();

[nainar, 2017/03/03 06:08:52]

This only goes over the descendants (ContainerNodes and ShadowRoot descendatnts)
only in the case we need Reattach. Should we maybe doing this in cases where
change >= UpdatePseudoElements to mimic the code in Element::recalcStyle()?

+    recalcDescendantStylesForLayout();
     return Reattach;
   }
 
   DCHECK(oldStyle);
 
   if (localChange != NoChange)
     updateCallbackSelectors(oldStyle.get(), newStyle.get());
 
   if (LayoutObject* layoutObject = this->layoutObject()) {
     if (localChange != NoChange ||
@@ skipping 24 matching lines @@
         return Inherit;
       newStyle->copyChildDependentFlagsFrom(*oldStyle);
     }
     if (oldStyle->hasPseudoElementStyle() || newStyle->hasPseudoElementStyle())
       return UpdatePseudoElements;
   }
 
   return localChange;
 }
 
+void Element::recalcStyleForLayout() {
+  if (!hasCustomStyleCallbacks()) {
+    StyleReattachData styleReattachData;
+    styleReattachData.computedStyle = styleForLayoutObject();
+    document().addStyleReattachData(*this, styleReattachData);
+  }
+  recalcShadowRootStylesForLayout();

[nainar, 2017/03/03 06:08:52]

Need to add a function here to deal with the relevant PseudoElement as well. 

void Element::recalcPseudoStyleForLayout(PseudoId pseudoId) {
  if (PseudoElement* element = pseudoElement(pseudoId))
      element->recalcStyleForLayout();
}

This comment applies to the code change above as well.

+  recalcDescendantStylesForLayout();
+}
+
+void Element::recalcShadowRootStylesForLayout() {
+  for (ShadowRoot* root = youngestShadowRoot(); root;
+       root = root->olderShadowRoot()) {
+      root->recalcDescendantStylesForLayout();
+  }
+}
+
 void Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
   DCHECK(parentNode());
 
   if (needsReattachLayoutTree()) {
     StyleReattachData styleReattachData =
         document().getStyleReattachData(*this);
     AttachContext reattachContext;
     reattachContext.resolvedStyle = styleReattachData.computedStyle.get();
     bool layoutObjectWillChange = needsAttach() || layoutObject();
@@ skipping 2144 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (hasRareData()) {
     visitor->traceWrappers(elementRareData());
   }
   ContainerNode::traceWrappers(visitor);
 }
 
 }  // namespace blink