rel="shortcut icon" => rel="icon"

`rel="shortcut icon"` used to be a workaround for some ancient browsers,
and doesn't seem like a correct markup according to the HTML spec today.

views/layout.erb

@@ -5,7 +5,7 @@
     <meta http-equiv="content-type" content="text/html; charset=utf-8" />
     <script src='<%= assets_path('application.js') %>' type='text/javascript'></script>
     <link href='<%= assets_path('application.css') %>' media='screen, projection, print' rel='stylesheet' type='text/css' />
-    <link rel="shortcut icon" type="image/png" href="<%= assets_path("favicon_#{coverage_css_class(result.source_files.covered_percent)}.png") %>" />
+    <link rel="icon" type="image/png" href="<%= assets_path("favicon_#{coverage_css_class(result.source_files.covered_percent)}.png") %>" />
   </head>
 
   <body<%= ' data-branch-coverage=true' if branchable_result? %>>