static unwrapTrustedHTML(safeHtml) {
    // Perform additional run-time type-checking to ensure that safeHtml is
    // indeed an instance of the expected type.  This provides some additional
    // protection against security bugs due to application code that disables
    // type checks. Specifically, the following checks are performed:
    // 1. The object is an instance of the expected type.
    // 2. The object is not an instance of a subclass.
    if (safeHtml instanceof SafeHtml && safeHtml.constructor === SafeHtml) {
      return safeHtml.privateDoNotAccessOrElseSafeHtmlWrappedValue_;
    } else {
      asserts.fail(
          `expected object of type SafeHtml, got '${safeHtml}' of type ` +
          goog.typeOf(safeHtml));
      return 'type_error:SafeHtml';
    }
  }
Unwraps value as TrustedHTML if supported or as a string if not.
@param {!SafeHtml} safeHtml
@return {!TrustedHTML|string}
@see SafeHtml.unwrap
@deprecated Use `safevalues.unwrapHtml` instead.