Revert "Add support for timezone offset and timezone name."

tests/corelib/date_time7_test.dart

-// Copyright (c) 2012, 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.
-
-// Test Date timeZoneName and timeZoneOffset getters.
-
-testUtc() {
-  var d = new Date.fromString("2012-03-04T03:25:38.123Z");
-  Expect.equals("UTC", d.timeZoneName);
-  Expect.equals(0, d.timeZoneOffset.inSeconds);
-}
-
-testLocal() {
-  checkOffset(String name, Duration offset) {
-    // Timezone abbreviations are not in bijection with their timezones.
-    // For example AST stands for "Arab Standard Time" (UTC+03), as well as
-    // "Arabian Standard Time" (UTC+04), or PST stands for Pacific Standard Time
-    // and Philippine Standard Time.
-    //
-    // Hardcode some common timezones.
-    if (name == "CET") {
-      Expect.equals(1, offset.inHours);
-    } else if (name == "CEST") {
-      Expect.equals(2, offset.inHours);
-    } else if (name == "GMT") {
-      Expect.equals(0, offset.inSeconds);
-    } else if (name == "EST") {
-      Expect.equals(-5, offset.inHours);
-    } else if (name == "EDT") {
-      Expect.equals(-4, offset.inHours);
-    } else if (name == "PDT") {
-      Expect.equals(-7, offset.inHours);
-    }
-  }
-
-  var d = new Date.fromString("2012-01-02T13:45:23");
-  String name = d.timeZoneName;
-  checkOffset(name, d.timeZoneOffset);
-
-  d = new Date.fromString("2012-07-02T13:45:23");
-  name = d.timeZoneName;
-  checkOffset(name, d.timeZoneOffset);
-}
-
-main() {
-  testUtc();
-  testLocal();
-}