Rename Date to DateTime.

BUG=http://dartbug.com/1424

Review URL: https://codereview.chromium.org//11770004

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart/pkg/logging@17549 260f80e4-7a28-3924-810f-c04153c831b5
diff --git a/lib/logging.dart b/lib/logging.dart
index 3713175..5e0a239 100644
--- a/lib/logging.dart
+++ b/lib/logging.dart
@@ -313,7 +313,7 @@
   final String loggerName;
 
   /** Time when this record was created. */
-  final Date time;
+  final DateTime time;
 
   /** Unique sequence number greater than all log records created before it. */
   final int sequenceNumber;
@@ -329,6 +329,6 @@
   LogRecord(
       this.level, this.message, this.loggerName,
       [time, this.exception, this.exceptionText]) :
-    this.time = (time == null) ? new Date.now() : time,
+    this.time = (time == null) ? new DateTime.now() : time,
     this.sequenceNumber = LogRecord._nextNumber++;
 }