getLineInfo = function(input, offset) {
    for (var line = 1, cur = 0;;) {
      lineBreak.lastIndex = cur;
      var match = lineBreak.exec(input);
      if (match && match.index < offset) {
        ++line;
        cur = match.index + match[0].length;
      } else {
        break;
      }
    }
    return {line: line, column: offset - cur};
  }
The `getLineInfo` function is mostly useful when the
`locations` option is off (for performance reasons) and you
want to find the line/column position for a given character
offset. `input` should be the code string that the offset refers
into.

@param {string} input
@param {number} offset
@returns {!Object}