Remove id attribute from PaymentItem in test.

PaymentItem no longer has an 'id' attribute. This patch removes the 'id'
attribute from one of the last places in the code base. This place was
missed in the patch that originally introduced the change.

BUG=587995

Review-Url: https://codereview.chromium.org/2025213002
Cr-Commit-Position: refs/heads/master@{#397026}
1 file changed