PaymentApp: Remove unncessary comments in PaymentRequestEvent.idl.

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

Index: third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
diff --git a/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl b/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
index 4c2cd0fbd821ad1fed8b59ebf077244ef2f0a9a2..802545dbb8773135cf8fdac04e150da2b9d5743e 100644
--- a/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
+++ b/third_party/WebKit/Source/modules/payments/PaymentRequestEvent.idl
@@ -9,19 +9,5 @@
     Exposed=ServiceWorker
 ] interface PaymentRequestEvent : ExtendableEvent {
     readonly attribute PaymentAppRequestData data;
-    // The payment app api spec says that respondWith() should take a union
-    // type as follows:
-    //  - respondWith((Promise<PaymentResponse> or PaymentResponse));
-    //
-    // But the web-idl spec says that Promise types are not distinguishable
-    // with any other type. Also, if we pass PaymentResponse to respondWith(),
-    // then it will just be cast to a promise immediately via Promise.resolve().
-    //
-    // We found existing case here:
-    //  - https://github.com/w3c/ServiceWorker/issues/724
-    //
-    // So, we should just use Promise<PaymentResponse> instead of union type.
-    // Related spec bug:
-    //  - https://github.com/w3c/webpayments-payment-apps-api/pull/71
     void respondWith(Promise<PaymentResponse> response);
 };