Rename `String.prototype.contains` to `String.prototype.includes`

docs/coverage.html

...ype/includes/String.prototype.includes_FailBadLocation.js

...totype/includes/String.prototype.includes_FailLocation.js

...e/includes/String.prototype.includes_FailMissingLetter.js

...g/prototype/includes/String.prototype.includes_Success.js

...e/includes/String.prototype.includes_SuccessNoLocation.js

...rototype/includes/String.prototype.includes_lengthProp.js