Rename 'items' into 'displayItems' in PaymentDetails.

This patch renames PaymentDetails.items into PaymentDetails.displayItems
to follow the spec updates. This patch does not introduce 100%
compliance with the spec. It is a simple search-and-replace patch.

https://w3c.github.io/browser-payment-api/specs/paymentrequest.html#paymentdetails-dictionary
https://github.com/w3c/browser-payment-api/commit/9ef1dd251089299fe3a50df6ff77f02821f7663f

BUG=587995

Review-Url: https://codereview.chromium.org/2028603004
Cr-Commit-Position: refs/heads/master@{#397576}
11 files changed