es-abstract tests blow the stack in node < 6

[ljharb]

See ljharb/es-abstract@156bf41.

When that flag is removed, tape will blow the stack running tests in es-abstract - nvm exec 6.0 npm run tests-only passes, but nvm exec 5 npm run tests-only fails. nvm exec 5 node test/bufferTestCases also fails if you want a smaller repro.

I haven't yet been able to improve tape's stack performance by enough to get the tests to complete in node < 6 without providing the --stack-size option.