In https://github.com/babel/babel/issues/9511 (and #9495 is another symptom), @PavelKastornyy reported a node crash becaue the JavaScript heap run out of memory. The problem was that their code was adding enumerable properties to `Object.prototype`: it is something that shouldn't be done, but Babel shouldn't make node crash if someone adds them.
I reduced down the problem to `for...in` loops in `@babel/traverse` that grew the memory consumption exponentially because of that unexpected properties.
* babel/parser: test helpers: when test fails with an exception and both reference output file and options.json file do not exist, write a simple options.json with the error message to expect when such a file doesn't exist yet. This completes the `jest -u` capability for new tests which are expected to *fail*.
