Make slots in non-shadow trees participate in a flat tree

third_party/WebKit/Source/core/dom/shadow/FlatTreeTraversal.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 50 matching lines @@
     const Node* node,
     TraversalDirection direction) {
   if (!node)
     return nullptr;
   for (const Node* sibling = node; sibling;
        sibling = (direction == TraversalDirectionForward
                       ? sibling->nextSibling()
                       : sibling->previousSibling())) {
     if (isHTMLSlotElement(*sibling)) {
       const HTMLSlotElement& slot = toHTMLSlotElement(*sibling);
-      if (!slot.supportsDistribution()) {
-        const_cast<HTMLSlotElement&>(slot).updateDistributedNodesManually();
+      if (slot.supportsDistribution()) {
+        if (Node* found = (direction == TraversalDirectionForward
+                               ? slot.firstDistributedNode()
+                               : slot.lastDistributedNode()))
+          return found;
+        continue;
       }
-      if (Node* found = (direction == TraversalDirectionForward
-                             ? slot.firstDistributedNode()
-                             : slot.lastDistributedNode()))
-        return found;
-      continue;
     }
     if (node->isInV0ShadowTree())
       return v0ResolveDistributionStartingAt(*sibling, direction);
     return const_cast<Node*>(sibling);
   }
   return nullptr;
 }
 
 Node* FlatTreeTraversal::v0ResolveDistributionStartingAt(
     const Node& node,
     TraversalDirection direction) {
-  DCHECK(!isHTMLSlotElement(node));
+  DCHECK(!isHTMLSlotElement(node) ||
+         !toHTMLSlotElement(node).supportsDistribution());
   for (const Node* sibling = &node; sibling;
        sibling = (direction == TraversalDirectionForward
                       ? sibling->nextSibling()
                       : sibling->previousSibling())) {
     if (!isActiveInsertionPoint(*sibling))
       return const_cast<Node*>(sibling);
     const InsertionPoint& insertionPoint = toInsertionPoint(*sibling);
     if (Node* found = (direction == TraversalDirectionForward
                            ? insertionPoint.firstDistributedNode()
                            : insertionPoint.lastDistributedNode()))
@@ skipping 87 matching lines @@
   if (node.isChildOfV1ShadowHost()) {
     HTMLSlotElement* slot = finalDestinationSlotFor(node);
     if (!slot)
       return nullptr;
     return traverseParent(*slot);
   }
 
   Element* parent = node.parentElement();
   if (parent && isHTMLSlotElement(parent)) {
     HTMLSlotElement& slot = toHTMLSlotElement(*parent);
-    if (!slot.assignedNodes().isEmpty())
-      return nullptr;
-    return traverseParent(slot, details);
+    if (slot.supportsDistribution()) {
+      if (!slot.assignedNodes().isEmpty())
+        return nullptr;
+      return traverseParent(slot, details);
+    }
   }
 
   if (canBeDistributedToInsertionPoint(node))
     return traverseParentForV0(node, details);
 
   DCHECK(!shadowWhereNodeCanBeDistributedForV0(node));
   return traverseParentOrHost(node);
 }
 
 ContainerNode* FlatTreeTraversal::traverseParentForV0(
@@ skipping 170 matching lines @@
 
 Node& FlatTreeTraversal::lastWithinOrSelf(const Node& node) {
   assertPrecondition(node);
   Node* lastDescendant = lastWithin(node);
   Node& result = lastDescendant ? *lastDescendant : const_cast<Node&>(node);
   assertPostcondition(&result);
   return result;
 }
 
 }  // namespace blink