Revert 12494.

lib/coreimpl/date.dart

Index: lib/coreimpl/date.dart
===================================================================
--- lib/coreimpl/date.dart	(revision 12500)
+++ lib/coreimpl/date.dart	(working copy)
@@ -62,7 +62,7 @@
   static const int _MAX_MILLISECONDS_SINCE_EPOCH = 8640000000000000;
 
   DateImplementation.fromMillisecondsSinceEpoch(this.millisecondsSinceEpoch,
-                                                this.isUtc) {
+                                                [this.isUtc = false]) {
     if (millisecondsSinceEpoch.abs() > _MAX_MILLISECONDS_SINCE_EPOCH) {
       throw new IllegalArgumentException(millisecondsSinceEpoch);
     }
@@ -159,15 +159,14 @@
     return new Duration(milliseconds: ms - otherMs);
   }
 
-  // TODO(lrn): Make parameters not optional for the implementation class.
   external DateImplementation(int year,
-                              [int month = 1,
-                               int day = 1,
-                               int hour = 0,
-                               int minute = 0,
-                               int second = 0,
-                               int millisecond = 0,
-                               bool isUtc = false]);
+                              [int month,
+                               int day,
+                               int hour,
+                               int minute,
+                               int second,
+                               int millisecond,
+                               bool isUtc]);
   external DateImplementation.now();
   external static int _brokenDownDateToMillisecondsSinceEpoch(
       int years, int month, int day, int hour, int minute, int second,