static transformGeneratorBody(identifierGenerator, reporter, options, body,
                                name) {
    return new GeneratorTransformer(identifierGenerator, reporter, options).
        transformGeneratorBody(body, name);
  }
@param {UniqueIdentifierGenerator} identifierGenerator
@param {ErrorReporter} reporter
@param {Block} body
@param {IdentifierExpression} name
@return {Block}