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

sdk/lib/core/duration.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.
 
 part of dart.core;
 
 /**
  * A span of time, such as 27 days, 4 hours, 12 minutes, and 3 seconds.
  *
  * A `Duration` represents a difference from one point in time to another. The
@@ skipping 75 matching lines @@
    * All individual parts are allowed to be negative.
    * All arguments are 0 by default.
    */
   const Duration({int days: 0,
                   int hours: 0,
                   int minutes: 0,
                   int seconds: 0,
                   int milliseconds: 0,
                   int microseconds: 0})
       : this._microseconds(
-            days * MICROSECONDS_PER_DAY +
-            hours * MICROSECONDS_PER_HOUR +
-            minutes * MICROSECONDS_PER_MINUTE +
-            seconds * MICROSECONDS_PER_SECOND +
-            milliseconds * MICROSECONDS_PER_MILLISECOND +
+            MICROSECONDS_PER_DAY * days +
+            MICROSECONDS_PER_HOUR * hours +
+            MICROSECONDS_PER_MINUTE * minutes +
+            MICROSECONDS_PER_SECOND * seconds +
+            MICROSECONDS_PER_MILLISECOND * milliseconds +
             microseconds);
 
   // Fast path internal direct constructor to avoids the optional arguments and
   // [_microseconds] recomputation.
   const Duration._microseconds(this._duration);
 
   /**
    * Adds this Duration and [other] and
    * returns the sum as a new Duration object.
    */
@@ skipping 169 matching lines @@
   Duration abs() => new Duration._microseconds(_duration.abs());
 
   /**
    * Returns a new `Duration` representing this `Duration` negated.
    *
    * The returned `Duration` has the same length as this one, but will have the
    * opposite sign of this one.
    */
   Duration operator -() => new Duration._microseconds(-_duration);
 }