Add `package:js` to dependencies (#71)

diff --git a/.github/workflows/test-package.yml b/.github/workflows/test-package.yml
index fbf4b6a..288eff2 100644
--- a/.github/workflows/test-package.yml
+++ b/.github/workflows/test-package.yml
@@ -20,7 +20,7 @@
     strategy:
       fail-fast: false
       matrix:
-        sdk: [dev]
+        sdk: [stable, dev]
     steps:
       - uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8
       - uses: dart-lang/setup-dart@6a218f2413a3e78e9087f638a238f6b40893203d
@@ -47,7 +47,7 @@
       matrix:
         # Add macos-latest and/or windows-latest if relevant for this package.
         os: [ubuntu-latest]
-        sdk: [2.15.0, dev]
+        sdk: [stable, dev]
     steps:
       - uses: actions/checkout@93ea575cb5d8a053eaa0ac8fa3b40d7e05a33cc8
       - uses: dart-lang/setup-dart@6a218f2413a3e78e9087f638a238f6b40893203d
diff --git a/CHANGELOG.md b/CHANGELOG.md
index de98c86..55269a5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 - Send `fetch` requests instead of `XHR` requests.
 - Add an optional `debugKey` parameter to `SseClient` to include in logging.
+- Add a dependency on `package:js`.
+- Update the minimum Dart SDK version to `2.16.0`.
 
 ## 4.1.1
 
diff --git a/pubspec.yaml b/pubspec.yaml
index 17955de..b11d779 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,11 +7,12 @@
 repository: https://github.com/dart-lang/sse
 
 environment:
-  sdk: '>=2.15.0 <3.0.0'
+  sdk: '>=2.16.0 <3.0.0'
 
 dependencies:
   async: ^2.0.8
   collection: ^1.0.0
+  js: ^0.6.4
   logging: '>=0.11.3+2 <2.0.0'
   pool: ^1.5.0
   shelf: ^1.1.0