function diff_linesToCharsMunge_(text) {
    var chars = '';
    // Walk the text, pulling out a substring for each line.
    // text.split('\n') would would temporarily double our memory footprint.
    // Modifying text would create many large strings to garbage collect.
    var lineStart = 0;
    var lineEnd = -1;
    // Keeping our own length variable is faster than looking it up.
    var lineArrayLength = lineArray.length;
    while (lineEnd < text.length - 1) {
      lineEnd = text.indexOf('\n', lineStart);
      if (lineEnd == -1) {
        lineEnd = text.length - 1;
      }
      var line = text.substring(lineStart, lineEnd + 1);
      lineStart = lineEnd + 1;

      if (lineHash.hasOwnProperty ? lineHash.hasOwnProperty(line) :
          (lineHash[line] !== undefined)) {
        chars += String.fromCharCode(lineHash[line]);
      } else {
        chars += String.fromCharCode(lineArrayLength);
        lineHash[line] = lineArrayLength;
        lineArray[lineArrayLength++] = line;
      }
    }
    return chars;
  }
Split a text into an array of strings.  Reduce the texts to a string of
hashes where each Unicode character represents one line.
Modifies linearray and linehash through being a closure.
@param {string} text String to encode.
@return {string} Encoded string.
@private