PaymentRequest.abort() should return a promise.

third_party/WebKit/Source/modules/modules.gypi

 {
   'includes': [
     '../core/core_generated.gypi',
     'modules_generated.gypi',
   ],
   'variables': {
     # Experimental hooks for embedder to provide extra IDL and source files.
     #
     # Note: this is not a supported API. If you rely on this, you will be broken
     # from time to time as the code generator changes in backward incompatible
@@ skipping 1999 matching lines @@
       'indexeddb/IDBKeyPathTest.cpp',
       'indexeddb/IDBRequestTest.cpp',
       'indexeddb/IDBTransactionTest.cpp',
       'indexeddb/MockWebIDBDatabase.cpp',
       'indexeddb/MockWebIDBDatabase.h',
       'mediasession/MediaSessionTest.cpp',
       'mediastream/MediaConstraintsTest.cpp',
       'mediastream/RTCDataChannelTest.cpp',
       'notifications/NotificationDataTest.cpp',
       'notifications/NotificationResourcesLoaderTest.cpp',
+      'payments/AbortTest.cpp',
       'payments/PaymentAddressTest.cpp',
       'payments/PaymentRequestDetailsTest.cpp',
+      'payments/PaymentRequestTestBase.cpp',
+      'payments/PaymentRequestTestBase.h',
       'payments/PaymentRequestTest.cpp',
       'payments/PaymentRequestUpdateEventTest.cpp',
       'payments/PaymentResponseTest.cpp',
       'payments/PaymentTestHelper.cpp',
+      'payments/PaymentTestHelper.h',
       'payments/PaymentsValidatorsTest.cpp',
       'presentation/PresentationAvailabilityTest.cpp',
       'push_messaging/PushManagerTest.cpp',
       'push_messaging/PushMessageDataTest.cpp',
       'serviceworkers/ServiceWorkerContainerTest.cpp',
       'webaudio/AudioBasicProcessorHandlerTest.cpp',
       'webaudio/ConvolverNodeTest.cpp',
       'webaudio/DynamicsCompressorNodeTest.cpp',
       'webaudio/ScriptProcessorNodeTest.cpp',
       'webaudio/StereoPannerNodeTest.cpp',
       'webdatabase/QuotaTrackerTest.cpp',
       'websockets/DOMWebSocketTest.cpp',
       'websockets/DocumentWebSocketChannelTest.cpp',
     ],
   },
 }