Do not allocate SlotAssignment unless a shadowroot has a slot

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
  * rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
  * (http://www.torchmobile.com/)
  *
@@ skipping 2303 matching lines @@
       break;
     filteredInsertionPoints.push_back(insertionPoint);
   }
   return StaticNodeList::adopt(filteredInsertionPoints);
 }
 
 HTMLSlotElement* Node::assignedSlot() const {
   // assignedSlot doesn't need to call updateDistribution().
   DCHECK(!isPseudoElement());
   if (ShadowRoot* root = v1ShadowRootOfParent())
-    return root->ensureSlotAssignment().findSlot(*this);
+    return root->assignedSlotFor(*this);
   return nullptr;
 }
 
 HTMLSlotElement* Node::assignedSlotForBinding() {
   // assignedSlot doesn't need to call updateDistribution().
   if (ShadowRoot* root = v1ShadowRootOfParent()) {
     if (root->type() == ShadowRootType::Open)
-      return root->ensureSlotAssignment().findSlot(*this);
+      return root->assignedSlotFor(*this);
   }
   return nullptr;
 }
 
 void Node::setFocused(bool flag) {
   document().userActionElements().setFocused(this, flag);
 }
 
 void Node::setActive(bool flag) {
   document().userActionElements().setActive(this, flag);
@@ skipping 102 matching lines @@
     // Relevant DOM Standard:
     // https://dom.spec.whatwg.org/#concept-node-insert
     // - 6.1.2: If parent is a shadow host and node is a slotable, then assign a
     //   slot for node.
     // https://dom.spec.whatwg.org/#concept-node-remove
     // - 10. If node is assigned, then run assign slotables for node’s assigned
     //   slot.
 
     // Although DOM Standard requires "assign a slot for node / run assign
     // slotables" at this timing, we skip it as an optimization.
-    if (HTMLSlotElement* slot = root->ensureSlotAssignment().findSlot(*this))
+    if (HTMLSlotElement* slot = root->assignedSlotFor(*this))
       slot->didSlotChange(slotChangeType);
   } else {
     // Relevant DOM Standard:
     // https://dom.spec.whatwg.org/#concept-node-insert
     // - 6.1.3: If parent is a slot whose assigned nodes is the empty list, then
     //   run signal a slot change for parent.
     // https://dom.spec.whatwg.org/#concept-node-remove
     // - 11. If parent is a slot whose assigned nodes is the empty list, then
     //   run signal a slot change for parent.
     Element* parent = parentElement();
@@ skipping 94 matching lines @@
   if (node) {
     std::stringstream stream;
     node->printNodePathTo(stream);
     LOG(INFO) << stream.str();
   } else {
     LOG(INFO) << "Cannot showNodePath for <null>";
   }
 }
 
 #endif