[paymentrequest] Change the PaymentRequestUpdateEvent model to better match FetchEvent (#50)

Previously there was a bug in the event model where if a page didn't listen for the update event and call updatePaymentRequest then the user interface would be permanently disabled. This change modifies the model to mirror the way that the FetchEvent works in a ServiceWorker. If a page wishes to carry out an update then it calls updateWith and provides a promise that will settle when the page is ready to proceed. If it is resolved with a PaymentDetails dictionary then the payment request will be updated with the supplied information. If it is rejected then no update occurs and the request can continue. If the page does not listen for the event or does not call updateWith then the request can continue.

You can read this change in place in the spec [here](http://github.adrianba.net/paymentrequest/specs/paymentrequest.html).
You can view, comment on, or merge this pull request online at:

  https://github.com/WICG/paymentrequest/pull/50

-- Commit Summary --

  * Change the PaymentRequestUpdateEvent model to better match FetchEvent

-- File Changes --

    M specs/paymentrequest.html (91)

-- Patch Links --

https://github.com/WICG/paymentrequest/pull/50.patch
https://github.com/WICG/paymentrequest/pull/50.diff

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Reply to this email directly or view it on GitHub:
https://github.com/WICG/paymentrequest/pull/50