This aligns our implementation with the specification. Doing this
fixes a number of WPT tests because this sets
`m_ongoing_api_method_tracker` to null, avoiding an assertion that
previously caused a crash.
This allows us to disable test output, which performs expensive assert
tracking. This was making our imported tests run significantly slower
than tests run via `WPT.sh`.
Formatting the output ourselves also allows us to remove unnecessary
information from the test output.
This commit also rebaselines all existing imported WPT tests to follow
the new format.