binding: Reduces the binary size of binding's generated code.

third_party/WebKit/Source/bindings/templates/partial_interface.cpp

 {% extends 'interface_base.cpp' %}
 
+{% set has_prepare_prototype_and_interface_object =
+    unscopeables or has_conditional_attributes_on_prototype or
+    methods | conditionally_exposed(is_partial) %}
+{% set prepare_prototype_and_interface_object_func =
+    '%s::preparePrototypeAndInterfaceObject' % v8_class_or_partial
+    if has_prepare_prototype_and_interface_object
+    else 'nullptr' %}
+
 
 {##############################################################################}
 {% block prepare_prototype_and_interface_object %}
 {% from 'interface.cpp' import install_unscopeables with context %}
 {% from 'interface.cpp' import install_conditionally_enabled_attributes_on_prototype with context %}
 {% from 'methods.cpp' import install_conditionally_enabled_methods
         with context %}
+{% if has_prepare_prototype_and_interface_object %}
 void {{v8_class_or_partial}}::preparePrototypeAndInterfaceObject(v8::Local<v8::Context> context, const DOMWrapperWorld& world, v8::Local<v8::Object> prototypeObject, v8::Local<v8::Function> interfaceObject, v8::Local<v8::FunctionTemplate> interfaceTemplate)
 {
+#error No one is currently using a partial interface with context-dependent properties.  If you\'re planning to use it, please consult with the binding team: <blink-reviews-bindings@chromium.org>
     {{v8_class}}::preparePrototypeAndInterfaceObject(context, world, prototypeObject, interfaceObject, interfaceTemplate);
-{% if unscopeables or
-      has_conditional_attributes_on_prototype or
-      methods | conditionally_exposed(is_partial) %}
     v8::Isolate* isolate = context->GetIsolate();
-{% endif %}
 {% if unscopeables %}
     {{install_unscopeables() | indent}}
 {% endif %}
 {% if has_conditional_attributes_on_prototype %}
     {{install_conditionally_enabled_attributes_on_prototype() | indent}}
 {% endif %}
 {% if methods | conditionally_exposed(is_partial) %}
     {{install_conditionally_enabled_methods() | indent}}
 {% endif %}
 }
+{% endif %}
 
 {% endblock %}
 
 
 {##############################################################################}
 {% block partial_interface %}
 void {{v8_class_or_partial}}::initialize()
 {
     // Should be invoked from ModulesInitializer.
     {{v8_class}}::updateWrapperTypeInfo(
         &{{v8_class_or_partial}}::install{{v8_class}}Template,
-        &{{v8_class_or_partial}}::preparePrototypeAndInterfaceObject);
+        {{prepare_prototype_and_interface_object_func}});
     {% for method in methods %}
     {% if method.overloads and method.overloads.has_partial_overloads %}
     {{v8_class}}::register{{method.name | blink_capitalize}}MethodForPartialInterface(&{{cpp_class_or_partial}}V8Internal::{{method.name}}Method);
     {% endif %}
     {% endfor %}
 }
 
 {% endblock %}