Rename ElementData's attribute related methods for clarity

Source/web/WebElement.cpp

Index: Source/web/WebElement.cpp
diff --git a/Source/web/WebElement.cpp b/Source/web/WebElement.cpp
index d80c4e6564a80f711d1320b99726205852fece71..488605c1ce99538112f8827577308aa4b44b4b3d 100644
--- a/Source/web/WebElement.cpp
+++ b/Source/web/WebElement.cpp
@@ -126,14 +126,14 @@ WebString WebElement::attributeLocalName(unsigned index) const
 {
     if (index >= attributeCount())
         return WebString();
-    return constUnwrap<Element>()->attributeItem(index).localName();
+    return constUnwrap<Element>()->attributeAt(index).localName();
 }
 
 WebString WebElement::attributeValue(unsigned index) const
 {
     if (index >= attributeCount())
         return WebString();
-    return constUnwrap<Element>()->attributeItem(index).value();
+    return constUnwrap<Element>()->attributeAt(index).value();
 }
 
 WebString WebElement::innerText()