Get stack traces for errors in most shadowrealm tests
This uses the non-standard stack property of Error, if it is present, to
provide stack trace information to the caller of shadowRealmEvalAsync().
The stack trace isn't available in shadowrealm-in-serviceworker and
shadowrealm-in-audioworklet contexts, because they implement a fake
dynamic import with ShadowRealm.prototype.evaluate(), which will wrap any
errors from the imported module in a TypeError and clobber any stack info.
We could do it by adding a try/catch around the module text, but that
would mess with line and column numbers; for now, we'll leave it.