Version 2.12.0-73.0.dev

Merge commit '1cfe7dd6f618397002845f46630d358a319ab85d' into 'dev'
diff --git a/pkg/kernel/lib/src/tool/batch_util.dart b/pkg/kernel/lib/src/tool/batch_util.dart
index d0482f5..9412c80 100644
--- a/pkg/kernel/lib/src/tool/batch_util.dart
+++ b/pkg/kernel/lib/src/tool/batch_util.dart
@@ -3,7 +3,6 @@
 // BSD-style license that can be found in the LICENSE file.
 library kernel.batch_util;
 
-import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
diff --git a/tools/VERSION b/tools/VERSION
index c381e82..cb9c202 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 12
 PATCH 0
-PRERELEASE 72
+PRERELEASE 73
 PRERELEASE_PATCH 0
\ No newline at end of file