Add a reference to issue #50.

[msporny]

Add a reference to issue #50.

[adrianhopebailie]

@msporny For consistency, I think the issue markers for issues #50, #39 should follow a similar format as they both relate to payment app interface (one for native apps and the other for web based apps).

I would suggest the following text and would include this at an appropriate point in the section User Agent delegates payment request algorithm and possibly another reference in the complete() section as this refers to messages being passed back to the payment app.

Suggested text:

<p class="issue" data-number="50" title="It is unclear how the user agent will interface with 
a native payment app.">This specification should describe how the user-agent will pass the payment request data and the complete signal to a native payment app and also how 
it will receive the payment response from the payment app.</p>

[msporny]

@adrianhopebailie wrote:

For consistency, I think the issue markers for issues #50, #39 should follow a similar format as they both relate to payment app interface

Done. Used your language and preference to issue marker location.

[adrianba]

Merged as 1988c40