static fromConstant(styleSheet) {
    const styleSheetString = Const.unwrap(styleSheet);
    if (styleSheetString.length === 0) {
      return SafeStyleSheet.EMPTY;
    }
    // > is a valid character in CSS selectors and there's no strict need to
    // block it if we already block <.
    assert(
        !contains(styleSheetString, '<'),
        `Forbidden '<' character in style sheet string: ${styleSheetString}`);
    return SafeStyleSheet.createSafeStyleSheetSecurityPrivateDoNotAccessOrElse(
        styleSheetString);
  }
Creates a SafeStyleSheet object from a compile-time constant string.

`styleSheet` must not have any &lt; characters in it, so that
the syntactic structure of the surrounding HTML is not affected.

@param {!Const} styleSheet A compile-time-constant string from
    which to create a SafeStyleSheet.
@return {!SafeStyleSheet} A SafeStyleSheet object initialized to
    `styleSheet`.
@deprecated Use `safevalues.safeStyleSheet` instead.