Move 'if defined?' conditional to before 'require' statement for r2 gem

lib/sass/discourse_sass_compiler.rb

@@ -66,11 +66,13 @@ class DiscourseSassCompiler
     # Check if CSS needs to be RTLed after compilation
     # and run R2 gem on compiled CSS if true and R2 gem is available
     css_output = css
-    if !SiteSetting.allow_user_locale && SiteSetting.default_locale.in?(%w(he ar fa_IR))
-      begin
-        require 'r2'
-        css_output = R2.r2(css) if defined?(R2)
-      rescue; end
+    if defined?(R2)
+      if !SiteSetting.allow_user_locale && SiteSetting.default_locale.in?(%w(he ar fa_IR))
+        begin
+          require 'r2'
+          css_output = R2.r2(css)
+        rescue; end
+      end
     end
     css_output
   end