samples/poppopwin: upgrade to first-class sample

samples/pop_pop_win/web/platform_web.dart

 library ppw_platform_web;
 
 import 'dart:async';
 import 'dart:html';
-import 'dart:js' as js;
 import 'package:poppopwin/platform_target.dart';
 
 class PlatformWeb extends PlatformTarget {
   static const String _BIG_HASH = '#big';
   static const String _ABOUT_HASH = '#about';
 
   final StreamController _aboutController = new StreamController(sync: true);
 
   PlatformWeb() : super.base() {
     window.onPopState.listen((args) => _processUrlHash());
   }
 
   @override
   Future clearValues() {
     window.localStorage.clear();
     return new Future.value();
   }
 
   @override
   Future setValue(String key, String value) {
     window.localStorage[key] = value;
     return new Future.value();
   }
 
   @override
   Future<String> getValue(String key) =>
       new Future.value(window.localStorage[key]);
 
-  @override
-  void trackAnalyticsEvent(String category, String action, [String label,
-                                                            int value]) {
-    var args = ['send', 'event', category, action];
-    if(label != null) {
-      args.add(label);
-    }
-
-    if(value != null) {
-      assert(label != null);
-      args.add(value);
-    }
-
-    js.context.callMethod('ga', args);
-  }
-
   bool get renderBig => _urlHash == _BIG_HASH;
 
   bool get showAbout => _urlHash == _ABOUT_HASH;
 
   Stream get aboutChanged => _aboutController.stream;
 
   void toggleAbout([bool value]) {
-    final Location loc = window.location;
+    var loc = window.location;
     // ensure we treat empty hash like '#', which makes comparison easy later
-    final hash = loc.hash.length == 0 ? '#' : loc.hash;
+    var hash = loc.hash.length == 0 ? '#' : loc.hash;
 
-    final isOpen = hash == _ABOUT_HASH;
+    var isOpen = hash == _ABOUT_HASH;
     if(value == null) {
       // then toggle the current value
       value = !isOpen;
     }
 
     var targetHash = value ? _ABOUT_HASH : '#';
     if(targetHash != hash) {
       loc.assign(targetHash);
     }
     _aboutController.add(null);
   }
 
   String get _urlHash => window.location.hash;
 
   void _processUrlHash() {
-    final Location loc = window.location;
-    final hash = loc.hash;
-    final href = loc.href;
+    var loc = window.location;
+    var hash = loc.hash;
+    var href = loc.href;
 
     final History history = window.history;
     switch(hash) {
       case "#reset":
         assert(href.endsWith(hash));
         var newLoc = href.substring(0, href.length - hash.length);
 
         window.localStorage.clear();
 
         loc.replace(newLoc);
         break;
       case _BIG_HASH:
-        loc.reload();
+        if (!renderBig) loc.reload();
         break;
       case _ABOUT_HASH:
         _aboutController.add(null);
         break;
     }
   }
 }