Call Element::rebuildLayoutTree from Document::updateStyle directly

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 1837 matching lines @@
     if (hasRareData()) {
       ElementRareData* data = elementRareData();
       if (change != IndependentInherit)
         data->clearComputedStyle();
 
       if (change >= IndependentInherit) {
         if (ElementAnimations* elementAnimations = data->elementAnimations())
           elementAnimations->setAnimationStyleChange(false);
       }
     }
-    if (parentComputedStyle())
+    if (parentComputedStyle()) {
       change = recalcOwnStyle(change, nextTextSibling);
+    } else {
+      clearNeedsReattachLayoutTree();

[nainar, 2016/12/07 14:48:21]

In case we don't perform recalcOwnStyle we will never clear the
NeedsReattachLayoutTree flag which is set on the creation of each Node. Clear
that here. 

[Bugs Nash, 2016/12/07 23:21:44]

good explanation, would be useful in a code comment

[nainar, 2016/12/07 23:49:10]

Done locally.

+    }
     clearNeedsStyleRecalc();
-    clearNeedsReattachLayoutTree();
   }
 
   // If we reattached we don't need to recalc the style of our descendants
   // anymore.
   if ((change >= UpdatePseudoElements && change < Reattach) ||
       childNeedsStyleRecalc()) {
     SelectorFilterParentScope filterScope(*this);
     StyleSharingDepthScope sharingScope(*this);
 
     updatePseudoElement(PseudoIdBefore, change);
@@ skipping 11 matching lines @@
     updatePseudoElement(PseudoIdBackdrop, change);
 
     // If our children have changed then we need to force the first-letter
     // checks as we don't know if they effected the first letter or not.
     // This can be seen when a child transitions from floating to
     // non-floating we have to take it into account for the first letter.
     updatePseudoElement(PseudoIdFirstLetter,
                         childNeedsStyleRecalc() ? Force : change);
 
     clearChildNeedsStyleRecalc();
-    clearChildNeedsReattachLayoutTree();
   }
 
   if (hasCustomStyleCallbacks())
     didRecalcStyle(change);
 }
 
 PassRefPtr<ComputedStyle> Element::propagateInheritedProperties(
     StyleRecalcChange change) {
   if (change != IndependentInherit)
     return nullptr;
@@ skipping 39 matching lines @@
   } else {
     INCREMENT_STYLE_STATS_COUNTER(document().styleEngine(), stylesChanged, 1);
   }
 
   if (localChange == Reattach) {
     StyleReattachData styleReattachData;
     styleReattachData.computedStyle = std::move(newStyle);
     styleReattachData.nextTextSibling = nextTextSibling;
     document().addStyleReattachData(*this, styleReattachData);
     setNeedsReattachLayoutTree();
-    return rebuildLayoutTree();
+    return Reattach;
   }
 
   DCHECK(oldStyle);
 
   if (localChange != NoChange)
     updateCallbackSelectors(oldStyle.get(), newStyle.get());
 
   if (LayoutObject* layoutObject = this->layoutObject()) {
     if (localChange != NoChange ||
         pseudoStyleCacheIsInvalid(oldStyle.get(), newStyle.get())) {
@@ skipping 20 matching lines @@
         return Inherit;
       newStyle->copyChildDependentFlagsFrom(*oldStyle);
     }
     if (oldStyle->hasPseudoElementStyle() || newStyle->hasPseudoElementStyle())
       return UpdatePseudoElements;
   }
 
   return localChange;
 }
 
-StyleRecalcChange Element::rebuildLayoutTree() {
+void Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(parentNode());
+
   StyleReattachData styleReattachData = document().getStyleReattachData(*this);
   AttachContext reattachContext;
   reattachContext.resolvedStyle = styleReattachData.computedStyle.get();
   bool layoutObjectWillChange = needsAttach() || layoutObject();
 
-  // We are calling Element::rebuildLayoutTree() from inside
-  // Element::recalcOwnStyle where we set the NeedsReattachLayoutTree
-  // flag - so needsReattachLayoutTree() should always be true.
-  DCHECK(parentNode());
-  DCHECK(parentNode()->childNeedsReattachLayoutTree());
-  DCHECK(needsReattachLayoutTree());
-  reattachLayoutTree(reattachContext);
-  // Since needsReattachLayoutTree() is always true we go into
-  // reattachLayoutTree() which reattaches all the descendant
-  // sub-trees. At this point no child should need reattaching.
+  if (needsReattachLayoutTree()) {
+    reattachLayoutTree(reattachContext);
+  } else if (childNeedsReattachLayoutTree()) {
+    SelectorFilterParentScope filterScope(*this);
+    StyleSharingDepthScope sharingScope(*this);
+    reattachPseudoElementLayoutTree(PseudoIdBefore);
+    rebuildShadowRootLayoutTree();
+    rebuildDescendantLayoutTrees();
+    reattachPseudoElementLayoutTree(PseudoIdAfter);
+    reattachPseudoElementLayoutTree(PseudoIdBackdrop);
+    reattachPseudoElementLayoutTree(PseudoIdFirstLetter);
+  }
+  DCHECK(!needsReattachLayoutTree());
   DCHECK(!childNeedsReattachLayoutTree());
 
   if (layoutObjectWillChange || layoutObject()) {
     // nextTextSibling is passed on to recalcStyle from recalcDescendantStyles
     // 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(styleReattachData.nextTextSibling);
-    return Reattach;
   }
-  return ReattachNoLayoutObject;
+}
+
+void Element::rebuildShadowRootLayoutTree() {
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(!needsReattachLayoutTree());
+  for (ShadowRoot* root = youngestShadowRoot(); root;
+       root = root->olderShadowRoot()) {
+    if (root->needsReattachLayoutTree() || root->childNeedsReattachLayoutTree())
+      root->rebuildLayoutTree();
+  }
+}
+
+void Element::reattachPseudoElementLayoutTree(PseudoId pseudoId) {
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(!needsReattachLayoutTree());
+  if (PseudoElement* element = pseudoElement(pseudoId)) {
+    if (element->needsReattachLayoutTree() ||
+        element->childNeedsReattachLayoutTree())
+      element->rebuildLayoutTree();
+  }
 }
 
 void Element::updateCallbackSelectors(const ComputedStyle* oldStyle,
                                       const ComputedStyle* newStyle) {
   Vector<String> emptyVector;
   const Vector<String>& oldCallbackSelectors =
       oldStyle ? oldStyle->callbackSelectors() : emptyVector;
   const Vector<String>& newCallbackSelectors =
       newStyle ? newStyle->callbackSelectors() : emptyVector;
   if (oldCallbackSelectors.isEmpty() && newCallbackSelectors.isEmpty())
@@ skipping 1207 matching lines @@
   PseudoElement* element =
       document().styleEngine().ensureResolver().createPseudoElementIfNeeded(
           *this, pseudoId);
   if (!element)
     return;
 
   if (pseudoId == PseudoIdBackdrop)
     document().addToTopLayer(element, this);
   element->insertedInto(this);
   element->attachLayoutTree();
-

[Bugs Nash, 2016/12/07 23:21:44]

was this intentional?

[nainar, 2016/12/07 23:49:10]

Nope - haven't sanitized the code for erroneous formating issues. Fixed this
issue locally. 

   InspectorInstrumentation::pseudoElementCreated(element);
 
   ensureElementRareData().setPseudoElement(pseudoId, element);
 }
 
 PseudoElement* Element::pseudoElement(PseudoId pseudoId) const {
   return hasRareData() ? elementRareData()->pseudoElement(pseudoId) : nullptr;
 }
 
 LayoutObject* Element::pseudoElementLayoutObject(PseudoId pseudoId) const {
@@ skipping 831 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (hasRareData()) {
     visitor->traceWrappers(elementRareData());
   }
   ContainerNode::traceWrappers(visitor);
 }
 
 }  // namespace blink