Fix WebBluetooth generator to distinguish between different methods.

third_party/WebKit/LayoutTests/bluetooth/script-tests/service/get-same-object.js

 'use strict';
 promise_test(() => {
   return setBluetoothFakeAdapter('HeartRateAdapter')
     .then(() => requestDeviceWithKeyDown({
       filters: [{services: ['heart_rate']}]}))
     .then(device => device.gatt.connect())
     .then(gattServer => gattServer.getPrimaryService('heart_rate'))
     .then(service => Promise.all([
       service.CALLS([
         getCharacteristic('body_sensor_location')|
@@ skipping 11 matching lines @@
                       characteristics_arrays[i].length);
       }
 
       let base_set = new Set(characteristics_arrays[0]);
       for (let characteristics of characteristics_arrays) {
         characteristics.forEach(
           characteristic => assert_true(base_set.has(characteristic)));
       }
     });
 }, 'Calls to FUNCTION_NAME should return the same object.');