[dom] support iterable<> NodeList

Source/core/html/HTMLCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003-2008, 2011, 2012, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. All rights reserved.
  *
  * 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
  * version 2 of the License, or (at your option) any later version.
@@ skipping 22 matching lines @@
 #include "core/html/HTMLElement.h"
 #include "core/html/HTMLObjectElement.h"
 #include "core/html/HTMLOptionElement.h"
 #include "core/html/HTMLOptionsCollection.h"
 #include "core/html/HTMLTagCollection.h"
 #include "core/html/WindowNameCollection.h"
 #include "wtf/HashSet.h"
 
 namespace blink {
 
+namespace {
+
+class HTMLCollectionIterationSource final : public ValueIterable<Element*>::IterationSource {
+public:
+    explicit HTMLCollectionIterationSource(HTMLCollection* collection)
+        : m_collection(collection)
+    {
+    }
+
+    bool next(ScriptState* scriptState, Element*& value, ExceptionState& exceptionState) override
+    {
+        if (m_index >= m_collection->length()) {
+            value = nullptr;
+            return false;
+        }
+        value = m_collection->item(m_index);
+        return true;
+    }
+
+    DEFINE_INLINE_VIRTUAL_TRACE()
+    {
+        visitor->trace(m_collection);
+        ValueIterable<Element*>::IterationSource::trace(visitor);
+    }
+
+private:
+    const RefPtrWillBeMember<HTMLCollection> m_collection;
+};
+
+} // namespace
+
+ValueIterable<Element*>::IterationSource* HTMLCollection::startIteration(ScriptState*, ExceptionState&)
+{
+    return new HTMLCollectionIterationSource(this);
+}
+
 using namespace HTMLNames;
 
 static bool shouldTypeOnlyIncludeDirectChildren(CollectionType type)
 {
     switch (type) {
     case ClassCollectionType:
     case TagCollectionType:
     case HTMLTagCollectionType:
     case DocAll:
     case DocAnchors:
@@ skipping 445 matching lines @@
 }
 
 DEFINE_TRACE(HTMLCollection)
 {
     visitor->trace(m_namedItemCache);
     visitor->trace(m_collectionItemsCache);
     LiveNodeListBase::trace(visitor);
 }
 
 } // namespace blink