Rename Date to DateTime.

tests/standalone/io/file_test.dart

Index: tests/standalone/io/file_test.dart
diff --git a/tests/standalone/io/file_test.dart b/tests/standalone/io/file_test.dart
index 348791e7514fd44dc19c654e9c884c483dd1b2d4..4d7093d61b3eb5fd8d34574983846fdb1a55d7ad 100644
--- a/tests/standalone/io/file_test.dart
+++ b/tests/standalone/io/file_test.dart
@@ -1153,16 +1153,16 @@ class FileTest {
   static void testLastModified() {
     var port = new ReceivePort();
     new File(new Options().executable).lastModified().then((modified) {
-      Expect.isTrue(modified is Date);
-      Expect.isTrue(modified < new Date.now());
+      Expect.isTrue(modified is DateTime);
+      Expect.isTrue(modified < new DateTime.now());
       port.close();
     });
   }
 
   static void testLastModifiedSync() {
     var modified = new File(new Options().executable).lastModifiedSync();
-    Expect.isTrue(modified is Date);
-    Expect.isTrue(modified < new Date.now());
+    Expect.isTrue(modified is DateTime);
+    Expect.isTrue(modified < new DateTime.now());
   }
 
   // Test that opens the same file for writing then for appending to test