[Bindings][Refactoring] Move logics of preparePrototypeAndInterfaceObject from .tmpl to .py

third_party/WebKit/Source/bindings/templates/interface.h.tmpl

 {% filter format_blink_cpp_source_code %}
 
 {% include 'copyright_block.txt' %}
 #ifndef {{v8_class}}_h
 #define {{v8_class}}_h
 
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
@@ skipping 111 matching lines @@
   static const int eventListenerCacheIndex = v8DefaultWrapperInternalFieldCount + {{custom_internal_field_counter}};
   {% set custom_internal_field_counter = custom_internal_field_counter + 1 %}
   {% endif %}
   {# persistentHandleIndex must be the last field, if it is present.
      Detailed explanation: https://codereview.chromium.org/139173012
      FIXME: Remove this internal field, and share one field for either:
      * a persistent handle (if the object is in oilpan) or
      * a C++ pointer to the DOM object (if the object is not in oilpan) #}
   static const int internalFieldCount = v8DefaultWrapperInternalFieldCount + {{custom_internal_field_counter}};
   {# End custom internal fields #}
-  {% if unscopables or has_conditional_attributes_on_prototype or
-        methods | conditionally_exposed(is_partial) %}
+  {% if prepare_prototype_and_interface_object_func %}
   {{exported}}static void preparePrototypeAndInterfaceObject(v8::Local<v8::Context>, const DOMWrapperWorld&, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate);
   {% elif has_partial_interface %}
   {{exported}}static void preparePrototypeAndInterfaceObject(v8::Local<v8::Context>, const DOMWrapperWorld&, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate) {}
   {% endif %}
+
   {% if has_partial_interface %}
   {{exported}}static void updateWrapperTypeInfo(InstallTemplateFunction, InstallRuntimeEnabledFunction, PreparePrototypeAndInterfaceObjectFunction);
   {{exported}}static void install{{v8_class}}Template(v8::Isolate*, const DOMWrapperWorld&, v8::Local<v8::FunctionTemplate> interfaceTemplate);
   {% for method in methods if method.overloads and method.overloads.has_partial_overloads %}
   {{exported}}static void register{{method.name | blink_capitalize}}MethodForPartialInterface(void (*)(const v8::FunctionCallbackInfo<v8::Value>&));
   {% endfor %}
   {% endif %}
 
   {% for feature in origin_trial_features %}
 
@@ skipping 127 matching lines @@
 template <>
 struct V8TypeOf<{{cpp_class}}> {
   typedef {{v8_class}} Type;
 };
 
 }  // namespace blink
 
 #endif  // {{v8_class}}_h
 
 {% endfilter %}{# format_blink_cpp_source_code #}