Consistently cache ElementData::length() before loops

Source/core/xml/XPathStep.cpp

Index: Source/core/xml/XPathStep.cpp
diff --git a/Source/core/xml/XPathStep.cpp b/Source/core/xml/XPathStep.cpp
index 56d7d6907c9fbfd377e73f195c2fa5595f453f20..70f183e03f5158df43f45d0b323d8674f5b28f85 100644
--- a/Source/core/xml/XPathStep.cpp
+++ b/Source/core/xml/XPathStep.cpp
@@ -350,7 +350,8 @@ void Step::nodesInAxis(Node* context, NodeSet& nodes) const
             if (!contextElement->hasAttributes())
                 return;
 
-            for (unsigned i = 0; i < contextElement->attributeCount(); ++i) {
+            unsigned attributeCount = contextElement->attributeCount();
+            for (unsigned i = 0; i < attributeCount; ++i) {
                 RefPtr<Attr> attr = contextElement->ensureAttr(contextElement->attributeItem(i)->name());
                 if (nodeMatches(attr.get(), AttributeAxis, m_nodeTest))
                     nodes.append(attr.release());