Ensure a wrap / unwrap tests run in the same order

This PR changes replaces the Promise based wrap / unwrap tests
with an async/await approach. This allows us have a more consistent
expectations for all the test cases and reduce the chances of
flakiness.

This is specially important for WebKit, which compares the text
output of the test against a pre-defined expected.txt.

There shouldn't be any functional change in the test cases, neither
additions or removals.