Added full js & js_util packages

packages/js_util/example/js_util.dart

+import 'dart:html';
+
+import 'package:js_util/js_util.dart';
+
+void main() {
+  final jsObj = toJS({
+    'people': [
+      {'firstName': 'Kwang Yul', 'lastName': 'Seo'},
+      {'firstName': 'DoHyung', 'lastName': 'Kim'},
+      {'firstName': 'Kyusun', 'lastName': 'Kim'}
+    ]
+  });
+
+  final people = getValue(jsObj, 'people');
+  final firstPerson = people[0];
+  final text =
+      '${getValue(firstPerson, "firstName")} ${getValue(firstPerson, "lastName")}';
+  document.querySelector('#container').innerHtml = text;
+}
+