anchor.diff:      0x39, 0x36, 0x39, 0x37, 0x39, 0x38, 0x39, 0x39
     ];
   
  -  // Powers of 10 above 1000000 are indistinguishable.
  +  // Powers of 10 above 1000000 are indistinguishable by eye.
     static const int _POW_10_7  = 10000000;
     static const int _POW_10_8  = 100000000;
     static const int _POW_10_9  = 1000000000;
  -  static const int _POW_10_10 = 10000000000;
   
     // Find the number of decimal digits in a positive smi.
  +  // Never called with numbers < 100. These are handled before calling.
     static int _positiveBase10Length(var smi) {
       // A positive smi has length <= 19 if 63-bit,  <=10 if 31-bit.
       // Avoid comparing a 31-bit smi to a non-smi.
  
positive.code:   }
  
    // Find the number of decimal digits in a negative smi.
    static int _negativeBase10Length(var negSmi) {
      // A negative smi has length <= 19 if 63-bit, <=10 if 31-bit.
      // Avoid comparing a 31-bit smi to a non-smi.
  
negative.code:       if (smi < 1000000) return 6;
        return 7;
      }
      if (smi < _POW_10_8) return 8;
      if (smi < _POW_10_9) return 9;
      smi = smi ~/ _POW_10_9;
      // Handle numbers < 100 before calling recursively.
      if (smi < 10) return 10;
      if (smi < 100) return 11;
      return 9 + _positiveBase10Length(smi);
    }
  
    String toString() {
  