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

Source/bindings/templates/interface_base.cpp

 {% include 'copyright_block.txt' %}
 #include "config.h"
 {% filter conditional(conditional_string) %}
 #include "{{v8_class_or_partial}}.h"
 
 {% for filename in cpp_includes if filename != '%s.h' % cpp_class_or_partial %}
 #include "{{filename}}"
 {% endfor %}
 
 namespace blink {
@@ skipping 400 matching lines @@
     {% filter per_context_enabled(iterator_method.per_context_enabled_function) %}
     {% filter exposed(iterator_method.exposed_test) %}
     {% filter runtime_enabled(iterator_method.runtime_enabled_function) %}
     static const V8DOMConfiguration::SymbolKeyedMethodConfiguration symbolKeyedIteratorConfiguration = { v8::Symbol::GetIterator, {{cpp_class_or_partial}}V8Internal::iteratorMethodCallback, 0, V8DOMConfiguration::ExposedToAllScripts };
     V8DOMConfiguration::installMethod(isolate, prototypeTemplate, defaultSignature, v8::DontDelete, symbolKeyedIteratorConfiguration);
     {% endfilter %}{# runtime_enabled() #}
     {% endfilter %}{# exposed() #}
     {% endfilter %}{# per_context_enabled() #}
     {% endif %}
     {# End special operations #}
+    {% if unscopeables %}
+    v8::Local<v8::Context> context(isolate->GetCurrentContext());
+    v8::Local<v8::Object> unscopeables(v8::Object::New(isolate));
+    {% for name in unscopeables %}
+    unscopeables->ForceSet(context, v8AtomicString(isolate, "{{name}}"), v8::True(isolate));
+    {% endfor %}
+    prototypeTemplate->Set(v8::Symbol::GetUnscopables(isolate), unscopeables);

[haraken, 2015/04/20 14:00:13]

Should we check a return value of ForceSet and Set?

bashi@: What should we do when the ForceSet and Set fails? Just ignore, or
ToLocalChecked?

+    {% endif %}
     {% if has_custom_legacy_call_as_function %}
     functionTemplate->InstanceTemplate()->SetCallAsFunctionHandler({{v8_class}}::legacyCallCustom);
     {% endif %}
     {% if interface_name == 'HTMLAllCollection' %}
     {# Needed for legacy support of document.all #}
     functionTemplate->InstanceTemplate()->MarkAsUndetectable();
     {% endif %}
     {% for method in custom_registration_methods %}
     {# install_custom_signature #}
     {% filter conditional(method.conditional_string) %}
@@ skipping 70 matching lines @@
 {% endfor %}
 {% for attribute in attributes if attribute.is_implemented_in_private_script %}
 {{attribute_getter_implemented_in_private_script(attribute)}}
 {% if attribute.has_setter %}
 {{attribute_setter_implemented_in_private_script(attribute)}}
 {% endif %}
 {% endfor %}
 {% block partial_interface %}{% endblock %}
 } // namespace blink
 {% endfilter %}