[Web Payments] Should set stop propagation flag
in PaymentRequestUpdateEvent::updateWith.

reference from
https://w3c.github.io/browser-payment-api/#updatewith

set stop propagation flag is missing.
BUG=587995

Review-Url: https://codereview.chromium.org/2495713002
Cr-Commit-Position: refs/heads/master@{#431671}
1 file changed