Consistently cache ElementData::length() before loops

Source/core/page/PageSerializer.cpp

Index: Source/core/page/PageSerializer.cpp
diff --git a/Source/core/page/PageSerializer.cpp b/Source/core/page/PageSerializer.cpp
index 7f31c9c055639726f0477a0e03fa69a8af25ee07..e72a2af99ea944244db5d36f836a176ca23678b5 100644
--- a/Source/core/page/PageSerializer.cpp
+++ b/Source/core/page/PageSerializer.cpp
@@ -78,7 +78,8 @@ static bool isCharsetSpecifyingNode(const Node& node)
         return false;
     HTMLAttributeList attributes;
     if (element.hasAttributes()) {
-        for (unsigned i = 0; i < element.attributeCount(); ++i) {
+        unsigned attributeCount = element.attributeCount();
+        for (unsigned i = 0; i < attributeCount; ++i) {
             const Attribute* attribute = element.attributeItem(i);
             // FIXME: We should deal appropriately with the attribute if they have a namespace.
             attributes.append(std::make_pair(attribute->name().localName(), attribute->value().string()));