[wpt] Fix testdriver.js portability issues in digital-credentials/
Some testdriver.js implementations use postMessage() to send
testdriver commands from a cross-origin iframe to the testharness
browsing context. 0 and 1 must be respected for testdriver.js to
work in those environments.
This is a no-op change when running the tests with content shell, which
implements testdriver.js with nonstandard JS bindings.
The testdriver.js and testdriver-vendor.js must both be included ...
in the top-level test document when using testdriver from a different
context
Bug: None
Change-Id: Idacd0b65d03d4feb77883927a5d90e61eb59797b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5922668
Reviewed-by: Weizhong Xia weizhong@google.com
Commit-Queue: Jonathan Lee jonathanjlee@google.com
Cr-Commit-Position: refs/heads/main@{#1370211}