Revert of Add template parameter to ElementTraversal to iterate over Elements of a specific type

Source/build/scripts/templates/ElementTypeHelpers.h.tmpl

 {% from "macros.tmpl" import license -%}
 {{ license() }}
 
 #ifndef {{namespace}}ElementTypeHelpers_h
 #define {{namespace}}ElementTypeHelpers_h
 
 #include "core/dom/ContextFeatures.h"
 #include "core/dom/Element.h"
 #include "{{namespace}}Names.h"
 #include "RuntimeEnabledFeatures.h"
@@ skipping 13 matching lines @@
     if (!RuntimeEnabledFeatures::{{tag.runtimeEnabled}}Enabled())
         return false;
 {%- endif %}
     return element.hasTagName({{namespace}}Names::{{tag.name}}Tag);
 }
 inline bool is{{tag.interface}}(const Element* element) { ASSERT(element); return is{{tag.interface}}(*element); }
 inline bool is{{tag.interface}}(const Node& node) { return node.isElementNode() ? is{{tag.interface}}(toElement(node)) : false; }
 inline bool is{{tag.interface}}(const Node* node) { ASSERT(node); return node->isElementNode() ? is{{tag.interface}}(*toElement(node)) : false; }
 template <> inline bool isElementOfType<const {{tag.interface}}>(const Element& element) { return is{{tag.interface}}(element); }
 {% endfor %}
+// Type casting.
+template<typename T> inline T& toElement(Node& node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(isElementOfType<const T>(node));
+    return static_cast<T&>(node);
+}
+template<typename T> inline T* toElement(Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || isElementOfType<const T>(*node));
+    return static_cast<T*>(node);
+}
+template<typename T> inline const T& toElement(const Node& node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(isElementOfType<const T>(node));
+    return static_cast<const T&>(node);
+}
+template<typename T> inline const T* toElement(const Node* node)
+{
+    ASSERT_WITH_SECURITY_IMPLICATION(!node || isElementOfType<const T>(*node));
+    return static_cast<const T*>(node);
+}
+template<typename T, typename U> inline T* toElement(const RefPtr<U>& node) { return toElement<T>(node.get()); }
 
 // Using macros because the types are forward-declared and we don't want to use reinterpret_cast in the
 // casting functions above. reinterpret_cast would be unsafe due to multiple inheritence.
 {% for tag in tags|sort if not tag.multipleTagNames %}
 #define to{{tag.interface}}(x) WebCore::toElement<WebCore::{{tag.interface}}>(x)
 {% endfor %}
 } // WebCore
 
 #endif