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.
We were previously throwing an exception if the generated code was
throwing an exception before it hit the implementation of the interface.
Instead, we are meant to catch any exception, and wrap that in a
rejected promise.
For example, this was impacting the fixed test in this commit as an
exception was being thrown when invoking WebIDL::convert_to_int<T>
as the given number was out of range, and the [EnforceRange]
extended attribute decorates that attribute.
This same type of case is seen for a few tests in WPT.
