Add scrolling tabs to code subnav

app/assets/stylesheets/framework/nav.scss

@@ -342,6 +342,24 @@
   }
 }
 
+.scrolling-tabs-container {
+  position: relative;
+
+  .nav-links {
+    @include scrolling-links();
+
+    .fade-right {
+      @include fade(left, rgba(255, 255, 255, 0.4), $background-color);
+      right: 0;
+    }
+
+    .fade-left {
+      @include fade(right, rgba(255, 255, 255, 0.4), $background-color);
+      left: 0;
+    }
+  }
+}
+
 .nav-block {
   position: relative;
 

app/views/projects/commits/_head.html.haml

-%ul.nav-links.sub-nav
+.scrolling-tabs-container
+  %ul.nav-links.sub-nav.scrolling-tabs
     %div{ class: (container_class) }
+      .fade-left
       = nav_link(controller: %w(tree blob blame edit_tree new_tree find_file)) do
         = link_to project_files_path(@project) do
           Files
@@ -23,3 +25,4 @@
       = nav_link(controller: [:tags, :releases]) do
         = link_to namespace_project_tags_path(@project.namespace, @project) do
           Tags
+      .fade-right