[shared_preferences] Endorse web plugin. (#2390)

* Make shared_preferences example work on web

* [shared_preferences] Endorse web plugin

* format pubspec
diff --git a/packages/shared_preferences/shared_preferences/CHANGELOG.md b/packages/shared_preferences/shared_preferences/CHANGELOG.md
index 6ba1a25..7c8b275 100644
--- a/packages/shared_preferences/shared_preferences/CHANGELOG.md
+++ b/packages/shared_preferences/shared_preferences/CHANGELOG.md
@@ -1,3 +1,8 @@
+## 0.5.6
+
+* Support `web` by default.
+* Require Flutter SDK 1.12.13+hotfix.4 or greater.
+
 ## 0.5.5
 
 * Support macos by default.
diff --git a/packages/shared_preferences/shared_preferences/example/web/index.html b/packages/shared_preferences/shared_preferences/example/web/index.html
new file mode 100644
index 0000000..6eff9a7
--- /dev/null
+++ b/packages/shared_preferences/shared_preferences/example/web/index.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="UTF-8">
+  <title>example</title>
+</head>
+<body>
+  <script src="main.dart.js" type="application/javascript"></script>
+</body>
+</html>
diff --git a/packages/shared_preferences/shared_preferences/pubspec.yaml b/packages/shared_preferences/shared_preferences/pubspec.yaml
index 227d3b1..a2f486e 100644
--- a/packages/shared_preferences/shared_preferences/pubspec.yaml
+++ b/packages/shared_preferences/shared_preferences/pubspec.yaml
@@ -2,7 +2,7 @@
 description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences/shared_preferences
-version: 0.5.5
+version: 0.5.6
 
 flutter:
   plugin:
@@ -14,6 +14,8 @@
         pluginClass: FLTSharedPreferencesPlugin
       macos:
         default_package: shared_preferences_macos
+      web:
+        default_package: shared_preferences_web
 
 dependencies:
   meta: ^1.0.4
@@ -26,6 +28,7 @@
   # TODO(franciscojma): Revisit this (either update this part in the  design or the pub tool).
   # https://github.com/flutter/flutter/issues/46264
   shared_preferences_macos: ^0.0.1
+  shared_preferences_web: ^0.1.2
 
 dev_dependencies:
   flutter_test:
@@ -37,4 +40,4 @@
 
 environment:
   sdk: ">=2.0.0-dev.28.0 <3.0.0"
-  flutter: ">=1.12.8 <2.0.0"
+  flutter: ">=1.12.13+hotfix.4 <2.0.0"