* Run JSON tests with `trailingComma: "all"` * Add test of `parser: 'json', trailingComma: 'all'` with non-.json extension See https://github.com/prettier/prettier/issues/2308#issuecomment-311707801 * Force trailingComma option to "none" when parser is JSON This fixes https://github.com/prettier/prettier/issues/2308