Blockly.Dart['text_length'] = function(block) {
  // String length.
  var argument0 = Blockly.Dart.valueToCode(block, 'VALUE',
      Blockly.Dart.ORDER_UNARY_POSTFIX) || '\'\'';
  return [argument0 + '.length', Blockly.Dart.ORDER_UNARY_POSTFIX];