Merge pull request rails#10222 from senny/update_bundler_section_in_a…

…ssets_guide

docs, adjust the application.rb snippets to match the generated file.

Closes rails#10449

guides/source/asset_pipeline.md

@@ -815,18 +815,16 @@ end
 If you use the `assets` group with Bundler, please make sure that your `config/application.rb` has the following Bundler require statement:
 
 ```ruby
-if defined?(Bundler)
-  # If you precompile assets before deploying to production, use this line
-  Bundler.require *Rails.groups(:assets => %w(development test))
-  # If you want your assets lazily compiled in production, use this line
-  # Bundler.require(:default, :assets, Rails.env)
-end
+# If you precompile assets before deploying to production, use this line
+Bundler.require *Rails.groups(:assets => %w(development test))
+# If you want your assets lazily compiled in production, use this line
+# Bundler.require(:default, :assets, Rails.env)
 ```
 
-Instead of the old Rails 3.0 version:
+Instead of the generated version:
 
 ```ruby
-# If you have a Gemfile, require the gems listed there, including any gems
+# Require the gems listed in Gemfile, including any gems
 # you've limited to :test, :development, or :production.
-Bundler.require(:default, Rails.env) if defined?(Bundler)
+Bundler.require(:default, Rails.env)
 ```