Import w3c tests for the service workers

third_party/WebKit/LayoutTests/imported/wpt/service-workers/service-worker/resources/interfaces.js

 function verify_interface(name, instance, attributes) {
   assert_true(name in self,
               name + ' should be an defined type');
   if (instance) {
     assert_true(instance instanceof self[name],
                 instance + ' should be an instance of ' + name);
     Object.keys(attributes || {}).forEach(function(attribute) {
         var type = attributes[attribute];
         assert_true(attribute in instance,
                     attribute + ' should be an attribute of ' + name);
         assert_equals(typeof instance[attribute], type,
                       attribute + ' should be of type ' + type);
       });
   }
 }