Start working on Version 1.22 of Dart

BUG=
R=floitsch@google.com

Review URL: https://codereview.chromium.org/2552373003 .
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8b6290d..f573d16 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.21.0
+## 1.21.0 - 2016-12-07
 
 ### Language
 
diff --git a/tools/VERSION b/tools/VERSION
index ff9f90a..0bcd6b6 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -26,7 +26,7 @@
 #
 CHANNEL be
 MAJOR 1
-MINOR 21
+MINOR 22
 PATCH 0
 PRERELEASE 0
 PRERELEASE_PATCH 0