Version 2.2.1-dev.4.0

Merge commit '523e3789e05ea07cdd21feadb04dc8ea0174204e' into dev
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7146605..8aa7a1a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,10 +1,4 @@
-## 2.2.1-dev.XX.0
-(Add new changes here, and they will be copied to the change section for the
-  next dev version)
-
-### Language
-
-### Core library changes
+## 2.2.1-dev.4.0
 
 ### Dart VM
 
@@ -22,16 +16,12 @@
 * new lint: `prefer_if_elements_to_conditional_expressions`
 * new lint: `diagnostic_describe_all_properties`
 
-#### Other Tools
-
 ## 2.2.1-dev.3.1
 
 * Cherry-pick 245576a096a2da54ef21d664d37d1f50f6f8dbb7 to dev
 * Cherry-pick a47b4ad2b8683cc8a82aa0ff89da2db7a3be27a3 to dev
 * Cherry-pick 9a2b222cba94126591b5d985a42d40c704a73c90 to dev
 
-### Tool Changes
-
 #### dartfmt
 
 *   Tweak set literal formatting to follow other collection literals.
diff --git a/tools/VERSION b/tools/VERSION
index f6ed346..d0461b8 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -29,11 +29,11 @@
 #  * Deprecating an old ABI version:
 #     - increase OLDEST_SUPPORTED_ABI_VERSION to the version that is supported.
 #
-CHANNEL be
+CHANNEL dev
 MAJOR 2
 MINOR 2
 PATCH 1
-PRERELEASE 0
+PRERELEASE 4
 PRERELEASE_PATCH 0
 ABI_VERSION 2
 OLDEST_SUPPORTED_ABI_VERSION 1