It's possible for an async test to throw a Symbol (harness/async-gc.js
does this.) The Symbol ends up getting passed to $DONE in a
.then($DONE, $DONE) call. Previously, $DONE would then throw an exception
due to not being able to convert the Symbol to a string.
Verify that every test file which references a harness file using the
"includes" directive also contains at least one reference to a value
defined in the harness file.
To support this check, extend each harness file with a list of values
which it defines.
Previously, the error message generated by failed asynchronous tests was
generic and underspecified. Improve the format and explicitly document
it in project's interpreting guidelines.
Philip Chimento
Mike Pennisi
Rick Waldron
Mathias Bynens
Brian Terlson