Have HTMLCollection::item() return an Element as per specification

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 3bb3df2b0f652935bc8aed69128367a495072f08..41b552dc72ea61afe786facc891d2286fd6ab791 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -4226,7 +4226,7 @@ KURL Document::openSearchDescriptionURL()
         return KURL();
 
     RefPtr<HTMLCollection> children = head()->children();
-    for (unsigned i = 0; Node* child = children->item(i); i++) {
+    for (unsigned i = 0; Element* child = children->item(i); i++) {
         if (!child->hasTagName(linkTag))
             continue;
         HTMLLinkElement* linkElement = toHTMLLinkElement(child);
@@ -4484,7 +4484,7 @@ Vector<IconURL> Document::iconURLs(int iconTypesMask)
     RefPtr<HTMLCollection> children = head() ? head()->children() : 0;
     unsigned length = children ? children->length() : 0;
     for (unsigned i = 0; i < length; i++) {
-        Node* child = children->item(i);
+        Element* child = children->item(i);
         if (!child->hasTagName(linkTag))
             continue;
         HTMLLinkElement* linkElement = toHTMLLinkElement(child);