Add support in generate scripts to handle Conditional

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"
 
 namespace WebCore {
 // Type checking.
 {% for tag in tags|sort if not tag.multipleTagNames and not tag.noTypeHelpers %}
+{% filter enable_conditional(tag.Conditional) %}
 class {{tag.interface}};
 void is{{tag.interface}}(const {{tag.interface}}&); // Catch unnecessary runtime check of type known at compile time.
 void is{{tag.interface}}(const {{tag.interface}}*); // Catch unnecessary runtime check of type known at compile time.
 
 {# For HTML Elements, call hasLocalName() instead of hasTagName() to avoid checking the namespace unnecessarily #}
 {% if namespace == 'HTML' %}
 inline bool is{{tag.interface}}(const HTMLElement& element) {
     {% if tag.runtimeEnabled or tag.contextConditional %}
     if (element.isHTMLUnknownElement())
         return false;
@@ skipping 19 matching lines @@
 {% endif %}
 inline bool is{{tag.interface}}(const Element* element) { return element && is{{tag.interface}}(*element); }
 template<typename T> inline bool is{{tag.interface}}(const PassRefPtr<T>& node) { return is{{tag.interface}}(node.get()); }
 template<typename T> inline bool is{{tag.interface}}(const RefPtr<T>& node) { return is{{tag.interface}}(node.get()); }
 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) { return node && node->isElementNode() ? is{{tag.interface}}(*toElement(node)) : false; }
 template <> inline bool isElementOfType<const {{tag.interface}}>(const Element& element) { return is{{tag.interface}}(element); }
 {% if namespace == "HTML" %}
 template <> inline bool isElementOfType<const {{tag.interface}}>(const HTMLElement& element) { return is{{tag.interface}}(element); }
 {% endif %}
-
+{% endfilter %}
 {% endfor %}
 // 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 and not tag.noTypeHelpers %}
+{% filter enable_conditional(tag.Conditional) %}
 #define to{{tag.interface}}(x) WebCore::toElement<WebCore::{{tag.interface}}>(x)
+{% endfilter %}
 {% endfor %}
 } // WebCore
 
 #endif