Clarify a role of Shadow DOM related functions

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)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1155 matching lines @@
 
 static inline AtomicString makeIdForStyleResolution(const AtomicString& value, bool inQuirksMode)
 {
     if (inQuirksMode)
         return value.lowerASCII();
     return value;
 }
 
 void Element::attributeChanged(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue, AttributeModificationReason reason)
 {
-    if (ElementShadow* parentElementShadow = shadowWhereNodeCanBeDistributed(*this)) {
+    if (ElementShadow* parentElementShadow = shadowWhereNodeCanBeDistributedForV0(*this)) {
         if (shouldInvalidateDistributionWhenAttributeChanged(parentElementShadow, name, newValue))
             parentElementShadow->setNeedsDistributionRecalc();
     }
     if (name == HTMLNames::slotAttr && oldValue != newValue) {
         if (ShadowRoot* root = v1ShadowRootOfParent())
             root->ensureSlotAssignment().hostChildSlotNameChanged(oldValue, newValue);
     }
 
     parseAttribute(name, oldValue, newValue);
 
@@ skipping 99 matching lines @@
             elementData()->clearClass();
     }
 
     if (hasRareData())
         elementRareData()->clearClassListValueForQuirksMode();
 }
 
 bool Element::shouldInvalidateDistributionWhenAttributeChanged(ElementShadow* elementShadow, const QualifiedName& name, const AtomicString& newValue)
 {
     DCHECK(elementShadow);
+    if (elementShadow->isV1())
+        return false;
     const SelectRuleFeatureSet& featureSet = elementShadow->ensureSelectFeatureSet();
 
     if (name == HTMLNames::idAttr) {
         AtomicString oldId = elementData()->idForStyleResolution();
         AtomicString newId = makeIdForStyleResolution(newValue, document().inQuirksMode());
         if (newId != oldId) {
             if (!oldId.isEmpty() && featureSet.hasSelectorForId(oldId))
                 return true;
             if (!newId.isEmpty() && featureSet.hasSelectorForId(newId))
                 return true;
@@ skipping 2516 matching lines @@
 
 DEFINE_TRACE_WRAPPERS(Element)
 {
     if (hasRareData()) {
         visitor->traceWrappers(elementRareData());
     }
     ContainerNode::traceWrappers(visitor);
 }
 
 } // namespace blink