function parseShift(state) {
    var node, operators, name, fn, params;
    node = parseConversion(state);
    operators = {
      '<<': 'leftShift',
      '>>': 'rightArithShift',
      '>>>': 'rightLogShift'
    };

    while (operators.hasOwnProperty(state.token)) {
      name = state.token;
      fn = operators[name];
      getTokenSkipNewline(state);
      params = [node, parseConversion(state)];
      node = new OperatorNode(name, fn, params);
    }

    return node;
  }
Bitwise left shift, bitwise right arithmetic shift, bitwise right logical shift
@return {Node} node
@private