code: function findSourceInLine(fragment, url, line) {
          var source = getSource(url),
              re = new RegExp('\\b' + escapeRegExp(fragment) + '\\b'),
              m;
  
          line -= 1;
  
          if (source && source.length > line && (m = re.exec(source[line]))) {
              return m.index;
          }
  
          return null;
      }
docs: Determines at which column a code fragment occurs on a line of the
  source code.
  @param {string} fragment The code fragment.
  @param {string} url The URL to search.
  @param {(string|number)} line The line number to examine.
  @return {?number} The column number.