prepare for 0.12.20+10 (#589)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cba4bef..a0d2ad1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.12.20+10
+
+* Refactor for internal tools.
+
 ## 0.12.20+9
 
 * Introduce new flag `--chain-stack-traces` to conditionally chain stack traces.
diff --git a/pubspec.yaml b/pubspec.yaml
index 4cbd2eb..1afc8da 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: test
-version: 0.12.20+9
+version: 0.12.20+10
 author: Dart Team <misc@dartlang.org>
 description: A library for writing dart unit tests.
 homepage: https://github.com/dart-lang/test