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

Source/core/html/forms/RangeInputType.cpp

Index: Source/core/html/forms/RangeInputType.cpp
diff --git a/Source/core/html/forms/RangeInputType.cpp b/Source/core/html/forms/RangeInputType.cpp
index 55066fcc48871707f8d234f19cac199c48c9d8ab..f5a3fccf6c6fb471c1c70a6dcbd19b2909f19414 100644
--- a/Source/core/html/forms/RangeInputType.cpp
+++ b/Source/core/html/forms/RangeInputType.cpp
@@ -355,10 +355,10 @@ void RangeInputType::updateTickMarkValues()
     RefPtr<HTMLCollection> options = dataList->options();
     m_tickMarkValues.reserveCapacity(options->length());
     for (unsigned i = 0; i < options->length(); ++i) {
-        Node* node = options->item(i);
-        HTMLOptionElement* optionElement = toHTMLOptionElement(node);
+        Element* element = options->item(i);
+        HTMLOptionElement* optionElement = toHTMLOptionElement(element);
         String optionValue = optionElement->value();
-        if (!element().isValidValue(optionValue))
+        if (!this->element().isValidValue(optionValue))
             continue;
         m_tickMarkValues.append(parseToNumber(optionValue, Decimal::nan()));
     }