Prepare to publish (#296)

Drop -dev version suffix.
diff --git a/pkgs/shelf/CHANGELOG.md b/pkgs/shelf/CHANGELOG.md
index d877a0f..fc79618 100644
--- a/pkgs/shelf/CHANGELOG.md
+++ b/pkgs/shelf/CHANGELOG.md
@@ -1,4 +1,4 @@
-## 1.4.0-dev
+## 1.4.0
 
 * Add Response.unauthorized() constructor
 * Add `poweredByHeader` argument to `serve`, `serveRequests`, and
diff --git a/pkgs/shelf/pubspec.yaml b/pkgs/shelf/pubspec.yaml
index bc9cfe8..c71a35d 100644
--- a/pkgs/shelf/pubspec.yaml
+++ b/pkgs/shelf/pubspec.yaml
@@ -1,5 +1,5 @@
 name: shelf
-version: 1.4.0-dev
+version: 1.4.0
 description: >
   A model for web server middleware that encourages composition and easy reuse.
 repository: https://github.com/dart-lang/shelf/tree/master/pkgs/shelf