PaymentHandler: Change topLevelOrigin to topOrigin

The related spec was changed:
  https://github.com/w3c/payment-handler/pull/301

Bug: 840041
Change-Id: Ic76fffe0b974210edc3888378ded197d06e035b7
Reviewed-on: https://chromium-review.googlesource.com/1045705
Reviewed-by: Mathieu Perreault <[email protected]>
Reviewed-by: Ganggui Tang <[email protected]>
Reviewed-by: Kinuko Yasuda <[email protected]>
Commit-Queue: Jinho Bang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#557757}
23 files changed