[dom] support iterable<> NodeList

Source/core/html/HTMLCollection.h

Index: Source/core/html/HTMLCollection.h
diff --git a/Source/core/html/HTMLCollection.h b/Source/core/html/HTMLCollection.h
index 2270e882dae029a62ab36cefed8ec4d78d483826..1a21e0c90e9af532e35d58e6c83a5302cae754a9 100644
--- a/Source/core/html/HTMLCollection.h
+++ b/Source/core/html/HTMLCollection.h
@@ -24,6 +24,7 @@
 #ifndef HTMLCollection_h
 #define HTMLCollection_h
 
+#include "bindings/core/v8/Iterable.h"
 #include "core/CoreExport.h"
 #include "core/dom/LiveNodeListBase.h"
 #include "core/html/CollectionItemsCache.h"
@@ -32,7 +33,7 @@
 
 namespace blink {
 
-class CORE_EXPORT HTMLCollection : public RefCountedWillBeGarbageCollectedFinalized<HTMLCollection>, public ScriptWrappable, public LiveNodeListBase {
+class CORE_EXPORT HTMLCollection : public RefCountedWillBeGarbageCollectedFinalized<HTMLCollection>, public ScriptWrappable, public ValueIterable<Element*>, public LiveNodeListBase {
     DEFINE_WRAPPERTYPEINFO();
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLCollection);
 public:
@@ -147,6 +148,8 @@ private:
         document.unregisterNodeListWithIdNameCache(this);
     }
 
+    IterationSource* startIteration(ScriptState*, ExceptionState&) override;
+
     const unsigned m_overridesItemAfter : 1;
     const unsigned m_shouldOnlyIncludeDirectChildren : 1;
     mutable OwnPtrWillBeMember<NamedItemCache> m_namedItemCache;