Have NodeList::item() overrides return an Element* when appropriate

Have NodeList::item() overrides return an Element* when appropriate instead
of a generic Node*. This makes it clear to callers that these are actually
returning Elements and avoids unnecessary isElementNode() checks or casts
that look unsafe.

R=adamk@chromium.org, esprehn@chromium.org

Review URL: https://codereview.chromium.org/331863003

git-svn-id: svn://svn.chromium.org/blink/trunk@176239 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/dom/LiveNodeList.h

@@ -42,7 +42,7 @@ public:
         : LiveNodeListBase(ownerNode, rootType, invalidationType, collectionType) { }
 
     virtual unsigned length() const OVERRIDE FINAL { return m_collectionIndexCache.nodeCount(*this); }
-    virtual Node* item(unsigned offset) const OVERRIDE FINAL { return m_collectionIndexCache.nodeAt(*this, offset); }
+    virtual Element* item(unsigned offset) const OVERRIDE FINAL { return m_collectionIndexCache.nodeAt(*this, offset); }
     virtual bool elementMatches(const Element&) const = 0;
 
     virtual void invalidateCache(Document* oldDocument = 0) const OVERRIDE FINAL;

third_party/WebKit/Source/core/dom/NamedNodesCollection.cpp

@@ -34,7 +34,7 @@
 
 namespace WebCore {
 
-Node* NamedNodesCollection::item(unsigned index) const
+Element* NamedNodesCollection::item(unsigned index) const
 {
     if (index < m_nodes.size())
         return m_nodes[index].get();

third_party/WebKit/Source/core/dom/NamedNodesCollection.h

@@ -31,7 +31,7 @@
 #ifndef NamedNodesCollection_h
 #define NamedNodesCollection_h
 
-#include "core/dom/Node.h"
+#include "core/dom/Element.h"
 #include "core/dom/NodeList.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefPtr.h"
@@ -47,7 +47,7 @@ public:
     }
 
     virtual unsigned length() const OVERRIDE { return m_nodes.size(); }
-    virtual Node* item(unsigned) const OVERRIDE;
+    virtual Element* item(unsigned) const OVERRIDE;
 
     virtual void trace(Visitor*) OVERRIDE;
 

third_party/WebKit/Source/core/html/RadioNodeList.cpp

@@ -52,12 +52,11 @@ RadioNodeList::~RadioNodeList()
 #endif
 }
 
-static inline HTMLInputElement* toRadioButtonInputElement(Node& node)
+static inline HTMLInputElement* toRadioButtonInputElement(Element& element)
 {
-    ASSERT(node.isElementNode());
-    if (!isHTMLInputElement(node))
+    if (!isHTMLInputElement(element))
         return 0;
-    HTMLInputElement& inputElement = toHTMLInputElement(node);
+    HTMLInputElement& inputElement = toHTMLInputElement(element);
     if (!inputElement.isRadioButton() || inputElement.value().isEmpty())
         return 0;
     return &inputElement;
@@ -67,9 +66,9 @@ String RadioNodeList::value() const
 {
     if (m_onlyMatchImgElements)
         return String();
-    for (unsigned i = 0; i < length(); ++i) {
-        Node* node = item(i);
-        const HTMLInputElement* inputElement = toRadioButtonInputElement(*node);
+    unsigned length = this->length();
+    for (unsigned i = 0; i < length; ++i) {
+        const HTMLInputElement* inputElement = toRadioButtonInputElement(*item(i));
         if (!inputElement || !inputElement->checked())
             continue;
         return inputElement->value();
@@ -81,9 +80,9 @@ void RadioNodeList::setValue(const String& value)
 {
     if (m_onlyMatchImgElements)
         return;
-    for (unsigned i = 0; i < length(); ++i) {
-        Node* node = item(i);
-        HTMLInputElement* inputElement = toRadioButtonInputElement(*node);
+    unsigned length = this->length();
+    for (unsigned i = 0; i < length; ++i) {
+        HTMLInputElement* inputElement = toRadioButtonInputElement(*item(i));
         if (!inputElement || inputElement->value() != value)
             continue;
         inputElement->setChecked(true);