anchor.diff:    DartType get setterType => isMutable ? type : const BottomType();
   
     Location _getLocationInEnclosingFile(int offset) {
  -    return enclosingProgram.getLocation(fileUri, offset);
  +    return _getLocationInProgram(enclosingProgram, fileUri, offset);
     }
   }
   
  
positive.code:   }
  
    Location _getLocationInEnclosingFile(int offset) {
      return enclosingProgram.getLocation(fileUri, offset);
    }
  }
  
  
negative.code: /// other words, if this information (or any information it refers to) changes,
  /// static analysis and runtime behavior of the library are unaffected.
  const informative = null;
  
  Location _getLocationInProgram(Program program, String fileUri, int offset) {
    if (program != null) {
      return program.getLocation(fileUri, offset);
    } else {
      return new Location(fileUri, TreeNode.noOffset, TreeNode.noOffset);
    }
  }
  