PaymentHandler: Implement PaymentInstruments.has().

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

 // Copyright 2017 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/webpayments-payment-apps-api/#payment-instruments
 
 [
     RuntimeEnabled=PaymentApp,
     Exposed=ServiceWorker
 ] interface PaymentInstruments {
     [CallWith=ScriptState, ImplementedAs=deleteInstrument] Promise<boolean> delete(DOMString instrumentKey);
     [CallWith=ScriptState] Promise<PaymentInstrument> get(DOMString instrumentKey);
     Promise<sequence<DOMString>> keys();
-    Promise<boolean> has(DOMString instrumentKey);
+    [CallWith=ScriptState] Promise<boolean> has(DOMString instrumentKey);
     [CallWith=ScriptState, RaisesException] Promise<void> set(DOMString instrumentKey, PaymentInstrument details);
 };