IDL: Add support for [Unscopeable] on attributes and methods

Source/bindings/templates/interface.h

 {% include 'copyright_block.txt' %}
 #ifndef {{v8_class}}_h
 #define {{v8_class}}_h
 
 {% filter conditional(conditional_string) %}
 {% for filename in header_includes %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
@@ skipping 140 matching lines @@
        * 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 interface_name == 'Window' %}
     static bool namedSecurityCheckCustom(v8::Local<v8::Object> host, v8::Local<v8::Value> key, v8::AccessType, v8::Local<v8::Value> data);
     static bool indexedSecurityCheckCustom(v8::Local<v8::Object> host, uint32_t index, v8::AccessType, v8::Local<v8::Value> data);
     {% endif %}
     static void installConditionallyEnabledProperties(v8::Local<v8::Object>, v8::Isolate*){% if has_conditional_attributes %};
     {% else %} { }
     {% endif %}
-    static void installConditionallyEnabledMethods(v8::Local<v8::Object>, v8::Isolate*){% if conditionally_enabled_methods %};
+    static void preparePrototypeObject(v8::Isolate*, v8::Local<v8::Object>){% if unscopeables or conditionally_enabled_methods %};
     {% else %} { }
     {% endif %}
     {% if has_partial_interface %}
-    {{exported}}static void updateWrapperTypeInfo(InstallTemplateFunction, InstallConditionallyEnabledMethodsFunction);
+    {{exported}}static void updateWrapperTypeInfo(InstallTemplateFunction, PreparePrototypeObjectFunction);
     {{exported}}static void install{{v8_class}}Template(v8::Local<v8::FunctionTemplate>, v8::Isolate*);
     {% 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 %}
     {% if has_partial_interface %}
 
 private:
     static InstallTemplateFunction install{{v8_class}}TemplateFunction;
     {% endif %}
@@ skipping 25 matching lines @@
 {% endif %}
 template <>
 struct V8TypeOf<{{cpp_class}}> {
     typedef {{v8_class}} Type;
 };
 
 } // namespace blink
 {% endfilter %}
 
 #endif // {{v8_class}}_h