Can you provide example page that does not succeed? I agree that you should be able to call `new PaymentRequest(methods, details)` multiple times, but `request.show()` should not be called more than one at a time, right?

(from a discussion with mahmadi@; mahmadi@: please feel free to elaborate if I missed anything)

More details: this is based on how things are implemented in iOS. I'm not sure how it's done for other platforms, but it would be worth making sure it works.

For iOS: PaymentRequest objects can be created in the JavaScript, but it does not currently create PaymentRequests in the model, until show() is called. This is fine for now, as only one request can be shown at once, but as I'm working on adding canMakePayment, there can be multiple active PaymentRequests, which the code does not support.

Also for iOS: when the PaymentRequest constructor executes in JavaScript, it should call into the C++ code to create an object in the model, which should generate an ID for the request, and return that ID.