Use new is*Element() helper functions more in HTML code

Source/core/html/forms/RadioInputType.cpp

Index: Source/core/html/forms/RadioInputType.cpp
diff --git a/Source/core/html/forms/RadioInputType.cpp b/Source/core/html/forms/RadioInputType.cpp
index fc6da4939fac96c1ec9d81843fa8493622c4ce5f..7a90d2fad679dac692fdd4db8b4f66e48e19cef3 100644
--- a/Source/core/html/forms/RadioInputType.cpp
+++ b/Source/core/html/forms/RadioInputType.cpp
@@ -24,7 +24,7 @@
 
 #include "HTMLNames.h"
 #include "InputTypeNames.h"
-#include "core/dom/NodeTraversal.h"
+#include "core/dom/ElementTraversal.h"
 #include "core/events/KeyboardEvent.h"
 #include "core/events/MouseEvent.h"
 #include "core/html/HTMLInputElement.h"
@@ -83,15 +83,15 @@ void RadioInputType::handleKeydownEvent(KeyboardEvent* event)
 
     // We can only stay within the form's children if the form hasn't been demoted to a leaf because
     // of malformed HTML.
-    Node* node = &element();
-    while ((node = (forward ? NodeTraversal::next(*node) : NodeTraversal::previous(*node)))) {
+    HTMLElement* htmlElement = &element();
+    while ((htmlElement = (forward ? Traversal<HTMLElement>::next(*htmlElement) : Traversal<HTMLElement>::previous(*htmlElement)))) {
         // Once we encounter a form element, we know we're through.
-        if (node->hasTagName(formTag))
+        if (isHTMLFormElement(*htmlElement))
             break;
         // Look for more radio buttons.
-        if (!node->hasTagName(inputTag))
+        if (!isHTMLInputElement(*htmlElement))
             continue;
-        HTMLInputElement* inputElement = toHTMLInputElement(node);
+        HTMLInputElement* inputElement = toHTMLInputElement(htmlElement);
         if (inputElement->form() != element().form())
             break;
         if (inputElement->isRadioButton() && inputElement->name() == element().name() && inputElement->isFocusable()) {
@@ -128,9 +128,9 @@ bool RadioInputType::isKeyboardFocusable() const
     // Never allow keyboard tabbing to leave you in the same radio group. Always
     // skip any other elements in the group.
     Element* currentFocusedElement = element().document().focusedElement();
-    if (currentFocusedElement && currentFocusedElement->hasTagName(inputTag)) {
-        HTMLInputElement* focusedInput = toHTMLInputElement(currentFocusedElement);
-        if (focusedInput->isRadioButton() && focusedInput->form() == element().form() && focusedInput->name() == element().name())
+    if (isHTMLInputElement(currentFocusedElement)) {
+        HTMLInputElement& focusedInput = toHTMLInputElement(*currentFocusedElement);
+        if (focusedInput.isRadioButton() && focusedInput.form() == element().form() && focusedInput.name() == element().name())
             return false;
     }