anchor.diff:  
   Future<SqlResultSet> createTable(SqlTransaction transaction, String tableName,
       String columnName) {
  -  final completer = new Completer<SqlResultSet>();
  +  final completer = new Completer<SqlResultSet>.sync();
   
     final sql = 'CREATE TABLE $tableName ($columnName)';
     transaction.executeSql(sql, [],
  
positive.code: 
  Future<SqlResultSet> insert(SqlTransaction transaction, String tableName,
      String columnName, value) {
    final completer = new Completer<SqlResultSet>();
  
    final sql = 'INSERT INTO $tableName ($columnName) VALUES (?)';
    transaction.executeSql(sql, [value],
  
negative.code: 
  Future<SqlResultSet> dropTable(SqlTransaction transaction, String tableName,
      [bool ignoreFailure = false]) {
    final completer = new Completer<SqlResultSet>.sync();
  
    final sql = 'DROP TABLE $tableName';
    transaction.executeSql(sql, [],
  