function lessThanOrEqualTo(propertyName, expression) {
  return new LessThanOrEqualTo(propertyName, expression);
}
Creates a `<PropertyIsLessThanOrEqualTo>` comparison operator.

@param {!string} propertyName Name of the context property to compare.
@param {!number} expression The value to compare.
@return {!LessThanOrEqualTo} `<PropertyIsLessThanOrEqualTo>` operator.
@api