Measure the impact of a propsed change to createAttribute()

Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1984 matching lines @@
     if (oldAttrNode.get() == attrNode)
         return attrNode; // This Attr is already attached to the element.
 
     // InUseAttributeError: Raised if node is an Attr that is already an attribute of another Element object.
     // The DOM user must explicitly clone Attr nodes to re-use them in other elements.
     if (attrNode->ownerElement()) {
         exceptionState.throwDOMException(InUseAttributeError, "The node provided is an attribute node that is already an attribute of another Element; attribute nodes must be explicitly cloned.");
         return nullptr;
     }
 
+    if (!isHTMLElement() && attrNode->document().isHTMLDocument() && attrNode->name() != attrNode->name().lower())
+        UseCounter::count(document(), UseCounter::NonHTMLElementSetAttributeNodeFromHTMLDocumentNameNotLowercase);
+
     synchronizeAllAttributes();
     const UniqueElementData& elementData = ensureUniqueElementData();
 
     AttributeCollection attributes = elementData.attributes();
     size_t index = attributes.findIndex(attrNode->qualifiedName(), shouldIgnoreAttributeCase());
     AtomicString localName;
     if (index != kNotFound) {
         const Attribute& attr = attributes[index];
 
         // If the name of the ElementData attribute doesn't
@@ skipping 1414 matching lines @@
 {
 #if ENABLE(OILPAN)
     if (hasRareData())
         visitor->trace(elementRareData());
     visitor->trace(m_elementData);
 #endif
     ContainerNode::trace(visitor);
 }
 
 } // namespace blink