/**
 * The text content inside `<style>` is a special case. It is _only_ rendered by the LWC engine itself; <style> tags
 * are disallowed inside of templates. Also, we want to avoid over-escaping, since CSS containing strings like
 * `&amp;` and `&quot;` is not valid CSS (even when inside a `<style>` element).
 *
 * However, to avoid XSS attacks, we still need to check for things like `</style><script>alert("pwned")</script>`,
 * since a user could use that inside of a *.css file to break out of a <style> element.
 * @param contents CSS source to validate
 * @throws Throws if the contents provided are not valid.
 * @see https://github.com/salesforce/lwc/issues/3439
 * @example
 * validateStyleTextContents('div { color: red }') // Ok
 * validateStyleTextContents('</style><script>alert("pwned")</script>') // Throws
 */
export declare function validateStyleTextContents(contents: string): void;