Fix Windows time zone name extraction. Update API docs

sdk/lib/core/date_time.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;
 
 /**
  * An instant in time, such as July 20, 1969, 8:18pm GMT.
  *
  * Create a DateTime object by using one of the constructors
@@ skipping 646 matching lines @@
    * This value is at most
    * 8,640,000,000,000,000,000us (100,000,000 days) from the Unix epoch.
    * In other words: `microsecondsSinceEpoch.abs() <= 8640000000000000000`.
    *
    * Note that this value does not fit into 53 bits (the size of a IEEE double).
    * A JavaScript number is not able to hold this value.
    */
   external int get microsecondsSinceEpoch;
 
   /**
-   * The abbreviated time zone name&mdash;for example,
-   * [:"CET":] or [:"CEST":].
+   * The time zone name provided by the platform.
+   *
+   * On Unix-like systems this will probably be an abbreviation. On Windows
+   * this will probably be the full-name, e.g. "Pacific Standard Time".
    */
   external String get timeZoneName;
 
   /**
    * The time zone offset, which
    * is the difference between local time and UTC.
    *
    * The offset is positive for time zones east of UTC.
    *
    * Note, that JavaScript, Python and C return the difference between UTC and
@@ skipping 73 matching lines @@
    * In accordance with ISO 8601
    * a week starts with Monday, which has the value 1.
    *
    *     DateTime moonLanding = DateTime.parse("1969-07-20 20:18:00");
    *     assert(moonLanding.weekday == 7);
    *     assert(moonLanding.weekday == DateTime.SUNDAY);
    *
    */
   external int get weekday;
 }