Call Element::rebuildLayoutTree from Document::updateStyle directly

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 945e0dc673290e2e4f6a04363892934c68ea2543..cc1d397aa1aa561fd9b5f602560c0ba9359cbf72 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -1930,14 +1930,17 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
     }
     if (parentComputedStyle())
       change = recalcOwnStyle(change, nextTextSibling);
-    clearNeedsStyleRecalc();
-    clearNeedsReattachLayoutTree();
+    // Needed because the rebuildLayoutTree code needs to see what the
+    // styleChangeType() was on reattach roots. See Node::reattachLayoutTree()
+    // for an example.
+    if (change != Reattach)
+      clearNeedsStyleRecalc();
   }
 
-  // If we reattached we don't need to recalc the style of our descendants
-  // anymore.
-  if ((change >= UpdatePseudoElements && change < Reattach) ||
-      childNeedsStyleRecalc()) {
+  // If we are going to reattach we don't need to recalc the style of
+  // our descendants anymore.
+  if (change < Reattach &&
+      (change >= UpdatePseudoElements || childNeedsStyleRecalc())) {
     SelectorFilterParentScope filterScope(*this);
     StyleSharingDepthScope sharingScope(*this);
 
@@ -1963,7 +1966,6 @@ void Element::recalcStyle(StyleRecalcChange change, Text* nextTextSibling) {
                         childNeedsStyleRecalc() ? Force : change);
 
     clearChildNeedsStyleRecalc();
-    clearChildNeedsReattachLayoutTree();
   }
 
   if (hasCustomStyleCallbacks())
@@ -2023,7 +2025,7 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
     styleReattachData.nextTextSibling = nextTextSibling;
     document().addStyleReattachData(*this, styleReattachData);
     setNeedsReattachLayoutTree();
-    return rebuildLayoutTree();
+    return Reattach;
   }
 
   DCHECK(oldStyle);
@@ -2067,34 +2069,57 @@ StyleRecalcChange Element::recalcOwnStyle(StyleRecalcChange change,
   return localChange;
 }
 
-StyleRecalcChange Element::rebuildLayoutTree() {
+void Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
-  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()) {
+    StyleReattachData styleReattachData =
+        document().getStyleReattachData(*this);
+    AttachContext reattachContext;
+    reattachContext.resolvedStyle = styleReattachData.computedStyle.get();
+    bool layoutObjectWillChange = needsAttach() || layoutObject();
+    reattachLayoutTree(reattachContext);
+    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);
+    }
+  } else if (childNeedsReattachLayoutTree()) {
+    DCHECK(!needsReattachLayoutTree());
+    SelectorFilterParentScope filterScope(*this);
+    StyleSharingDepthScope sharingScope(*this);
+    reattachPseudoElementLayoutTree(PseudoIdBefore);
+    rebuildShadowRootLayoutTree();
+    rebuildChildrenLayoutTrees();
+    reattachPseudoElementLayoutTree(PseudoIdAfter);
+    reattachPseudoElementLayoutTree(PseudoIdBackdrop);
+    reattachPseudoElementLayoutTree(PseudoIdFirstLetter);
+  }
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  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;
+void Element::rebuildShadowRootLayoutTree() {
+  for (ShadowRoot* root = youngestShadowRoot(); root;
+       root = root->olderShadowRoot()) {
+    if (root->needsReattachLayoutTree() || root->childNeedsReattachLayoutTree())
+      root->rebuildLayoutTree();
+  }
+}
+
+void Element::reattachPseudoElementLayoutTree(PseudoId pseudoId) {
+  if (PseudoElement* element = pseudoElement(pseudoId)) {
+    if (element->needsReattachLayoutTree() ||
+        element->childNeedsReattachLayoutTree())
+      element->rebuildLayoutTree();
+  } else {
+    createPseudoElementIfNeeded(pseudoId);
   }
-  return ReattachNoLayoutObject;
 }
 
 void Element::updateCallbackSelectors(const ComputedStyle* oldStyle,