Migrate test block 7 to Dart 2.0.

tests/corelib_2/duration2_test.dart

 // Copyright (c) 2015, 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.
 
 import "package:expect/expect.dart";
 
 main() {
   // If the duration class multiplies "str" * microseconds-per-day (instead of
   // (microseconds-per-day * "str") it will try to build up a huge string and
   // terminate with an out-of-memory exception instead of an ArgumentError or
   // TypeError.
   // See dartbug.com/22309
 
   String longString = "str" * 1000;
-  Expect.throws(() => new Duration(days: longString),
+  Expect.throws(() => new Duration(/*@compile-error=unspecified*/days: longString),
       (e) => e is ArgumentError || e is TypeError || e is NoSuchMethodError);
-  Expect.throws(() => new Duration(hours: longString),
+  Expect.throws(() => new Duration(/*@compile-error=unspecified*/hours: longString),
       (e) => e is ArgumentError || e is TypeError || e is NoSuchMethodError);
-  Expect.throws(() => new Duration(minutes: longString),
+  Expect.throws(() => new Duration(/*@compile-error=unspecified*/minutes: longString),
       (e) => e is ArgumentError || e is TypeError || e is NoSuchMethodError);
-  Expect.throws(() => new Duration(seconds: longString),
+  Expect.throws(() => new Duration(/*@compile-error=unspecified*/seconds: longString),
       (e) => e is ArgumentError || e is TypeError || e is NoSuchMethodError);
-  Expect.throws(() => new Duration(milliseconds: longString),
+  Expect.throws(() => new Duration(/*@compile-error=unspecified*/milliseconds: longString),
       (e) => e is ArgumentError || e is TypeError || e is NoSuchMethodError);
-  Expect.throws(() => new Duration(microseconds: longString),
+  Expect.throws(() => new Duration(/*@compile-error=unspecified*/microseconds: longString),
       (e) => e is ArgumentError || e is TypeError || e is NoSuchMethodError);
 }