Move HTMLLabelElement-related complexity out of Element

Source/core/html/HTMLLabelElement.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, 2010 Apple Inc. All rights reserved.
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 182 matching lines @@
 }
 
 void HTMLLabelElement::accessKeyAction(bool sendMouseEvents)
 {
     if (HTMLElement* element = control())
         element->accessKeyAction(sendMouseEvents);
     else
         HTMLElement::accessKeyAction(sendMouseEvents);
 }
 
+void HTMLLabelElement::updateLabel(TreeScope& scope, const AtomicString& oldForAttributeValue, const AtomicString& newForAttributeValue)
+{
+    if (!inDocument())
+        return;
+
+    if (oldForAttributeValue == newForAttributeValue)
+        return;
+
+    if (!oldForAttributeValue.isEmpty())
+        scope.removeLabel(oldForAttributeValue, toHTMLLabelElement(this));
+    if (!newForAttributeValue.isEmpty())
+        scope.addLabel(newForAttributeValue, toHTMLLabelElement(this));
+}
+
+void HTMLLabelElement::attributeWillChange(const QualifiedName& name, const AtomicString& oldValue, const AtomicString& newValue)
+{
+    if (name == HTMLNames::forAttr) {
+        TreeScope& scope = treeScope();
+        if (scope.shouldCacheLabelsByForAttribute())
+            updateLabel(scope, oldValue, newValue);
+    }
+    HTMLElement::attributeWillChange(name, oldValue, newValue);
+}
+
+Node::InsertionNotificationRequest HTMLLabelElement::insertedInto(ContainerNode* insertionPoint)
+{
+    InsertionNotificationRequest result = HTMLElement::insertedInto(insertionPoint);
+    if (insertionPoint->isInTreeScope()) {
+        TreeScope& scope = insertionPoint->treeScope();
+        if (scope == treeScope() && scope.shouldCacheLabelsByForAttribute())
+            updateLabel(scope, nullAtom, fastGetAttribute(forAttr));
+    }
+    return result;
+}
+
+void HTMLLabelElement::removedFrom(ContainerNode* insertionPoint)
+{
+    if (insertionPoint->isInTreeScope() && treeScope() == document()) {
+        TreeScope& treeScope = insertionPoint->treeScope();
+        if (treeScope.shouldCacheLabelsByForAttribute())
+            updateLabel(treeScope, fastGetAttribute(forAttr), nullAtom);
+    }
+    HTMLElement::removedFrom(insertionPoint);
+}
+
 } // namespace