stable release for null safety (#29)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7d6b6fb..558aeb1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+### 3.0.0
+
+* First stable null safe release.
+
 ### 3.0.0-nullsafety.4
 
 * Update supported SDK range.
diff --git a/pubspec.yaml b/pubspec.yaml
index 484dd2d..5480397 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: platform
-version: 3.0.0-nullsafety.4
+version: 3.0.0
 description: A pluggable, mockable platform abstraction for Dart.
 homepage: https://github.com/google/platform.dart