Function assert_readonly

deps/v8/test/wasm-js/third_party/testharness.js:1499–1513

(object, property_name, description)

    expose(_assert_inherits("assert_idl_attribute"), "assert_idl_attribute");

    function assert_readonly(object, property_name, description)
    {
         var initial_value = object[property_name];
         try {
             //Note that this can have side effects in the case where
             //the property has PutForwards
             object[property_name] = initial_value + "a"; //XXX use some other value here?
             assert(same_value(object[property_name], initial_value),
                    "assert_readonly", description,
                    "changing property ${p} succeeded",
                    {p:property_name});
         } finally {
             object[property_name] = initial_value;
         }
    }
    expose(assert_readonly, "assert_readonly");

    /**