Style guide tweak

src/site/articles/style-guide/index.markdown

 ---
 layout: article
 title: "Dart Style Guide"
 rel:
   author: bob-nystrom
 description: "Follow these guidelines for consistent, readable Dart code."
 has-permalinks: true
 article:
   written_on: 2011-10-27
   updated_on: 2014-10-27
@@ skipping 623 matching lines @@
 final urlScheme = new RegExp('^([a-z]+):');
 
 class Dice {
   static final numberGenerator = new Random();
 }
 {% endprettify %}
 </div>
 
 <div class="bad">
 {% prettify dart %}
-const pi = 3.14;
+const PI = 3.14;
 const kDefaultTimeout = 1000;
 final URL_SCHEME = new RegExp('^([a-z]+):');
 
 class Dice {
   static final NUMBER_GENERATOR = new Random();
 }
 {% endprettify %}
 </div>
 
 <aside class="alert alert-info" markdown="1">
@@ skipping 835 matching lines @@
 
 var fooList = [
   1,
   2,
   3];
 
 var fooList = [1, 2,
   3, 4];
 {% endprettify %}
 </div>