PaymentRequest.abort() should return a promise.

third_party/WebKit/Source/modules/payments/PaymentRequest.idl

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // https://w3c.github.io/browser-payment-api/specs/paymentrequest.html#paymentrequest-interface
 // http://crbug.com/587995
 
 [
     RuntimeEnabled=PaymentRequest,
     Constructor(sequence<PaymentMethodData> methodData, PaymentDetails details, optional PaymentOptions options),
     ConstructorCallWith=ScriptState,
     RaisesException=Constructor,
     ActiveScriptWrappable,
     DependentLifetime,
 ] interface PaymentRequest : EventTarget {
     [CallWith=ScriptState] Promise<PaymentResponse> show();
-    [RaisesException] void abort();
+    [CallWith=ScriptState] Promise<void> abort();
 
     [ImplementedAs=getShippingAddress] readonly attribute PaymentAddress? shippingAddress;
     readonly attribute DOMString? shippingOption;
 
     attribute EventHandler onshippingaddresschange;
     attribute EventHandler onshippingoptionchange;
 };