Add support in generate scripts to handle Conditional

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

 {% from "macros.tmpl" import license %}
 {{ license() }}
 
 #ifndef {{namespace}}{{suffix}}Names_h
 #define {{namespace}}{{suffix}}Names_h
 
 {% if suffix %}
 #include "{{namespace}}Names.h"
 {% else %}
 {% if export %}
 #include "platform/PlatformExport.h"
 {% endif %}
 #include "wtf/text/AtomicString.h"
 {% endif %}
 
 namespace WebCore {
 namespace {{namespace}}Names {
 
 #ifndef {{namespace|to_macro_style}}_NAMES_HIDE_GLOBALS
 
 {% for entry in entries|sort %}
+{% filter enable_conditional(entry.Conditional) %}
 {% if export %}
 {{export}} extern const WTF::AtomicString& {{entry|symbol}};
 {% else %}
 extern const WTF::AtomicString {{entry|symbol}};
 {% endif %}
+{% endfilter %}
 {% endfor %}
 
 #endif // {{namespace|to_macro_style}}_NAMES_HIDE_GLOBALS
 
 {{export}} void init{{suffix}}();
 
 } // {{namespace}}Names
 } // WebCore
 
 #endif