Implement WebBluetooth descriptor.writeValue()

third_party/WebKit/LayoutTests/bluetooth/script-tests/descriptor/io-op-device-disconnects-before.js

 'use strict';
 promise_test(() => {
   let val = new Uint8Array([1]);
   return setBluetoothFakeAdapter('DisconnectingHealthThermometerAdapter')
       .then(() => requestDeviceWithKeyDown({
               filters: [{services: ['health_thermometer']}],
               optionalServices: [request_disconnection_service_uuid]
             }))
       .then(device => device.gatt.connect())
       .then(gattServer => {
         let measurement_interval;
         return gattServer.getPrimaryService('health_thermometer')
             .then(ht => ht.getCharacteristic('measurement_interval'))
             .then(
                 characteristic =>
                     characteristic.getDescriptor(user_description.name))
             .then(d => user_description = d)
             .then(() => get_request_disconnection(gattServer))
             .then(requestDisconnection => requestDisconnection())
             .then(
                 () => assert_promise_rejects_with_message(
-                    user_description.CALLS([readValue()]),
+                    user_description.CALLS([readValue()|writeValue(val)]),
                     new DOMException(
                         'GATT Server is disconnected. Cannot perform GATT operations.',
                         'NetworkError')));
       });
 }, 'Device disconnects before FUNCTION_NAME. Reject with NetworkError.');