corelib: Don't blow up in memory if a duration receives a string as argument.

tests/corelib/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
+
+  Expect.throws(() => new Duration(days: "str"),
+                (e) => e is ArgumentError || e is TypeError);
+  Expect.throws(() => new Duration(hours: "str"),
+                (e) => e is ArgumentError || e is TypeError);
+  Expect.throws(() => new Duration(minutes: "str"),
+                (e) => e is ArgumentError || e is TypeError);
+  Expect.throws(() => new Duration(seconds: "str"),
+                (e) => e is ArgumentError || e is TypeError);
+  Expect.throws(() => new Duration(milliseconds: "str"),
+                (e) => e is ArgumentError || e is TypeError);
+  // No check for `microseconds` since it doesn't throw in unchecked mode and

[sra1, 2015/02/10 16:02:30]

Add the check.  Surely it does throw -  0 + "str" should be an error.

milliseconds: "str" probably doesn't result in out-of-memory either with a 3k
string.

[floitsch, 2015/02/10 16:39:16]

Done.

+  // wouldn't yield an out-of-memory error.
+}