Add an example (dart-lang/stream_transform#86)

Bumps up the score on pub
diff --git a/pkgs/stream_transform/example/index.html b/pkgs/stream_transform/example/index.html
new file mode 100644
index 0000000..aecdc09
--- /dev/null
+++ b/pkgs/stream_transform/example/index.html
@@ -0,0 +1,11 @@
+<html>
+  <head>
+    <script defer src="main.dart.js" type="application/javascript"></script>
+  </head>
+  <body>
+    <input id="first_input"><br>
+    <input id="second_input"><br>
+    <p id="output">
+    </p>
+  </body>
+</html>
diff --git a/pkgs/stream_transform/example/main.dart b/pkgs/stream_transform/example/main.dart
new file mode 100644
index 0000000..4ed53d8
--- /dev/null
+++ b/pkgs/stream_transform/example/main.dart
@@ -0,0 +1,26 @@
+// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:html';
+
+import 'package:stream_transform/stream_transform.dart';
+
+void main() {
+  var firstInput = document.querySelector('#first_input') as InputElement;
+  var secondInput = document.querySelector('#second_input') as InputElement;
+  var output = document.querySelector('#output');
+
+  _inputValues(firstInput)
+      .combineLatest(_inputValues(secondInput),
+          (first, second) => 'First: $first, Second: $second')
+      .tap((v) {
+    print('Saw: $v');
+  }).forEach((v) {
+    output.text = v;
+  });
+}
+
+Stream<String> _inputValues(InputElement element) => element.onKeyUp
+    .debounce(const Duration(milliseconds: 100))
+    .map((_) => element.value);
diff --git a/pkgs/stream_transform/pubspec.yaml b/pkgs/stream_transform/pubspec.yaml
index 7542887..803cc2e 100644
--- a/pkgs/stream_transform/pubspec.yaml
+++ b/pkgs/stream_transform/pubspec.yaml
@@ -10,3 +10,6 @@
 dev_dependencies:
   pedantic: ^1.5.0
   test: ^1.0.0
+  # Example
+  build_runner: ^1.0.0
+  build_web_compilers: ^2.0.0