Make Element::attributes() less error-prone and simplify call sites

Source/core/dom/NamedNodeMap.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)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 40 matching lines @@
     return m_element->getAttributeNode(name);
 }
 
 PassRefPtrWillBeRawPtr<Node> NamedNodeMap::getNamedItemNS(const AtomicString& namespaceURI, const AtomicString& localName) const
 {
     return m_element->getAttributeNodeNS(namespaceURI, localName);
 }
 
 PassRefPtrWillBeRawPtr<Node> NamedNodeMap::removeNamedItem(const AtomicString& name, ExceptionState& exceptionState)
 {
-    size_t index = m_element->hasAttributes() ? m_element->attributes().findIndex(name, m_element->shouldIgnoreAttributeCase()) : kNotFound;
+    size_t index = m_element->attributes().findIndex(name, m_element->shouldIgnoreAttributeCase());
     if (index == kNotFound) {
         exceptionState.throwDOMException(NotFoundError, "No item with name '" + name + "' was found.");
         return nullptr;
     }
     return m_element->detachAttribute(index);
 }
 
 PassRefPtrWillBeRawPtr<Node> NamedNodeMap::removeNamedItemNS(const AtomicString& namespaceURI, const AtomicString& localName, ExceptionState& exceptionState)
 {
-    size_t index = m_element->hasAttributes() ? m_element->attributes().findIndex(QualifiedName(nullAtom, localName, namespaceURI)) : kNotFound;
+    size_t index = m_element->attributes().findIndex(QualifiedName(nullAtom, localName, namespaceURI));
     if (index == kNotFound) {
         exceptionState.throwDOMException(NotFoundError, "No item with name '" + namespaceURI + "::" + localName + "' was found.");
         return nullptr;
     }
     return m_element->detachAttribute(index);
 }
 
 PassRefPtrWillBeRawPtr<Node> NamedNodeMap::setNamedItem(Node* node, ExceptionState& exceptionState)
 {
     if (!node) {
@@ skipping 10 matching lines @@
     return m_element->setAttributeNode(toAttr(node), exceptionState);
 }
 
 PassRefPtrWillBeRawPtr<Node> NamedNodeMap::setNamedItemNS(Node* node, ExceptionState& exceptionState)
 {
     return setNamedItem(node, exceptionState);
 }
 
 PassRefPtrWillBeRawPtr<Node> NamedNodeMap::item(unsigned index) const
 {
-    if (!m_element->hasAttributes())
-        return nullptr;
     AttributeCollection attributes = m_element->attributes();
     if (index >= attributes.size())
         return nullptr;
     return m_element->ensureAttr(attributes[index].name());
 }
 
 size_t NamedNodeMap::length() const
 {
-    if (!m_element->hasAttributes())
-        return 0;
     return m_element->attributes().size();
 }
 
 void NamedNodeMap::trace(Visitor* visitor)
 {
     visitor->trace(m_element);
 }
 
 } // namespace blink