Revert "Remove deprecated classes and functions in Date."

lib/compiler/implementation/lib/mockimpl.dart

Index: lib/compiler/implementation/lib/mockimpl.dart
diff --git a/lib/compiler/implementation/lib/mockimpl.dart b/lib/compiler/implementation/lib/mockimpl.dart
index 08648b963210d8818313dab8ad876dd86f21a81e..4dccbcdc021ed75be2a2fbb96deda524be8cbcf2 100644
--- a/lib/compiler/implementation/lib/mockimpl.dart
+++ b/lib/compiler/implementation/lib/mockimpl.dart
@@ -166,6 +166,18 @@ class StringBase {
   }
 }
 
+class TimeZoneImplementation implements TimeZone {
+  const TimeZoneImplementation.utc() : isUtc = true;
+  TimeZoneImplementation.local() : isUtc = false;
+
+  bool operator ==(Object other) {
+    if (!(other is TimeZoneImplementation)) return false;
+    return isUtc == other.isUtc;
+  }
+
+  final bool isUtc;
+}
+
 class DateImplementation implements Date {
   final int value;
   final bool _isUtc;
@@ -184,6 +196,17 @@ class DateImplementation implements Date {
     _asJs();
   }
 
+  DateImplementation.withTimeZone(int years,
+                                  int month,
+                                  int day,
+                                  int hours,
+                                  int minutes,
+                                  int seconds,
+                                  int milliseconds,
+                                  TimeZoneImplementation timeZone)
+      : this(years, month, day, hours, minutes, seconds, milliseconds,
+             timeZone.isUtc);
+
   DateImplementation.now()
       : _isUtc = false,
         value = Primitives.dateNow() {
@@ -273,6 +296,13 @@ class DateImplementation implements Date {
     return new DateImplementation.fromEpoch(value, true);
   }
 
+  Date changeTimeZone(TimeZone targetTimeZone) {
+    if (targetTimeZone === null) {
+      targetTimeZone = new TimeZoneImplementation.local();
+    }
+    return new Date.fromEpoch(value, targetTimeZone.isUtc);
+  }
+
   String get timeZoneName() {
     if (isUtc()) return "UTC";
     return Primitives.getTimeZoneName(this);