Check that interface constructors and default class constructors are compatible.

client/samples/total/src/DateTimeUtils.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class DateUtils {
   static final int DAYS_FROM_1900_TO_1970 = 25569;
   static final int MILLISECONDS_PER_DAY = 86400000;
   static final int MILLISECONDS_PER_HOUR = 3600000;
   static Date _EPOCH;
 
   // Return the 1899-12-30 spreadsheet epoch
   static Date get EPOCH() {
     if (_EPOCH == null) {
       _EPOCH = new Date(1899, 12, 30, 0, 0, 0, 0);
     }
     return _EPOCH;
   }
 
   static double getDate(int year, int month, int day) {
     Date dateTime = new Date(year, month, day, 12, 0, 0, 0);
     int milliseconds = dateTime.difference(EPOCH).inMilliseconds;
     double days = (milliseconds / MILLISECONDS_PER_DAY).floor();
     return days;
   }
 
   // Return a Date object corresponding to the given number of days after 1899-12-30.
   static Date getDateTime(double daysSince18991230) {
     double daysSinceEpoch = daysSince18991230 - DAYS_FROM_1900_TO_1970;
-    double millisSinceEpoch = daysSinceEpoch * MILLISECONDS_PER_DAY;
+    int millisSinceEpoch = (daysSinceEpoch * MILLISECONDS_PER_DAY).toInt();
     return new Date.fromEpoch(millisSinceEpoch, const TimeZone.utc());
   }
 
   static double getTime(int hour, int minute, int second) {
     Date dateTime = new Date(1899, 12, 30, hour, minute, second, 0);
     int milliseconds = dateTime.difference(EPOCH).inMilliseconds;
     double days = milliseconds / MILLISECONDS_PER_DAY;
     return days;
   }
 
@@ skipping 74 matching lines @@
   static double today() => now().floor();
 
   // Parse an integer, stripping leading zeros to avoid an octal parsing bug.
   static int _parseInt(String s) {
     while (s.length > 1 && s.charCodeAt(0) == StringUtils.ZERO) {
       s = s.substring(1, s.length);
     }
     return Math.parseInt(s);
   }
 }