Make it obvious an HTMLFormControlsCollection can only contain HTMLElements

Source/core/html/HTMLFormControlsCollection.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2010, 2011, 2012 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 63 matching lines @@
 {
     unsigned i = 0;
     for (; i < associatedElements.size(); ++i) {
         FormAssociatedElement* associatedElement = associatedElements[i];
         if (associatedElement->isEnumeratable() && toHTMLElement(associatedElement) == element)
             break;
     }
     return i;
 }
 
-Element* HTMLFormControlsCollection::virtualItemAfter(Element* previous) const
+HTMLElement* HTMLFormControlsCollection::virtualItemAfter(Element* previous) const
 {
     const FormAssociatedElement::List& associatedElements = formControlElements();
     unsigned offset;
     if (!previous)
         offset = 0;
     else if (m_cachedElement == previous)
         offset = m_cachedElementOffsetInArray + 1;
     else
         offset = findFormAssociatedElement(associatedElements, previous) + 1;
 
@@ skipping 33 matching lines @@
         HTMLImageElement* element = (*imageElementsArray)[i];
         if (element->fastGetAttribute(attrName) == name) {
             UseCounter::count(element->document(), UseCounter::FormNameAccessForImageElement);
             return element;
         }
     }
 
     return 0;
 }
 
-Element* HTMLFormControlsCollection::namedItem(const AtomicString& name) const
+HTMLElement* HTMLFormControlsCollection::namedItem(const AtomicString& name) const
 {
     // http://msdn.microsoft.com/workshop/author/dhtml/reference/methods/nameditem.asp
     // This method first searches for an object with a matching id
     // attribute. If a match is not found, the method then searches for an
     // object with a matching name attribute, but only on those elements
     // that are allowed a name attribute.
     const WillBeHeapVector<RawPtrWillBeMember<HTMLImageElement> >* imagesElements = isHTMLFieldSetElement(ownerNode()) ? 0 : &formImageElements();
     if (HTMLElement* item = firstNamedItem(formControlElements(), imagesElements, idAttr, name))
         return item;
 
@@ skipping 63 matching lines @@
 void HTMLFormControlsCollection::supportedPropertyNames(Vector<String>& names)
 {
     // http://www.whatwg.org/specs/web-apps/current-work/multipage/common-dom-interfaces.html#htmlformcontrolscollection-0:
     // The supported property names consist of the non-empty values of all the id and name attributes
     // of all the elements represented by the collection, in tree order, ignoring later duplicates,
     // with the id of an element preceding its name if it contributes both, they differ from each
     // other, and neither is the duplicate of an earlier entry.
     HashSet<AtomicString> existingNames;
     unsigned length = this->length();
     for (unsigned i = 0; i < length; ++i) {
-        Element* element = item(i);
+        HTMLElement* element = item(i);
         ASSERT(element);
         const AtomicString& idAttribute = element->getIdAttribute();
         if (!idAttribute.isEmpty()) {
             HashSet<AtomicString>::AddResult addResult = existingNames.add(idAttribute);
             if (addResult.isNewEntry)
                 names.append(idAttribute);
         }
         const AtomicString& nameAttribute = element->getNameAttribute();
         if (!nameAttribute.isEmpty()) {
             HashSet<AtomicString>::AddResult addResult = existingNames.add(nameAttribute);
             if (addResult.isNewEntry)
                 names.append(nameAttribute);
         }
     }
 }
 
 void HTMLFormControlsCollection::trace(Visitor* visitor)
 {
     visitor->trace(m_cachedElement);
     HTMLCollection::trace(visitor);
 }
 
 }