Fix Profile > Design live-updating

`ui_blue` wasn't added to the list of classes to remove, so if a user
changed to that theme, any subsequent changes wouldn't be live-updated.

This change refactors Gitlab::Theme a bit to make it harder for this to
happen in the future with new themes.

app/views/profiles/update.js.erb

 // Remove body class for any previous theme, re-add current one
-$('body').removeClass('ui_basic ui_mars ui_modern ui_gray ui_color light_theme dark_theme')
+$('body').removeClass('<%= Gitlab::Theme.body_classes %>')
 $('body').addClass('<%= app_theme %> <%= theme_type %>')
 
 // Re-render the header to reflect the new theme

lib/gitlab/theme.rb

@@ -7,33 +7,44 @@ module Gitlab
     COLOR  = 5 unless const_defined?(:COLOR)
     BLUE   = 6 unless const_defined?(:BLUE)
 
-    def self.css_class_by_id(id)
-      themes = {
-        BASIC  => "ui_basic",
-        MARS   => "ui_mars",
-        MODERN => "ui_modern",
-        GRAY   => "ui_gray",
-        COLOR  => "ui_color",
-        BLUE   => "ui_blue"
+    def self.classes
+      @classes ||= {
+        BASIC  => 'ui_basic',
+        MARS   => 'ui_mars',
+        MODERN => 'ui_modern',
+        GRAY   => 'ui_gray',
+        COLOR  => 'ui_color',
+        BLUE   => 'ui_blue'
       }
+    end
 
+    def self.css_class_by_id(id)
       id ||= Gitlab.config.gitlab.default_theme
-
-      themes[id]
+      classes[id]
     end
 
-    def self.type_css_class_by_id(id)
-      types = {
+    def self.types
+      @types ||= {
         BASIC  => 'light_theme',
         MARS   => 'dark_theme',
         MODERN => 'dark_theme',
         GRAY   => 'dark_theme',
-        COLOR  => 'dark_theme'
+        COLOR  => 'dark_theme',
+        BLUE   => 'light_theme'
       }
+    end
 
+    def self.type_css_class_by_id(id)
       id ||= Gitlab.config.gitlab.default_theme
-
       types[id]
     end
+
+    # Convenience method to get a space-separated String of all the theme
+    # classes that mighty be applied to the `body` element
+    #
+    # Returns a String
+    def self.body_classes
+      (classes.values + types.values).uniq.join(' ')
+    end
   end
 end