Special case Regexp instead of strings

Author: rafaelfranca

lib/rails/dom/testing/assertions/selector_assertions/substitution_context.rb

@@ -24,10 +24,12 @@ def match(matches, attribute, matcher)
             private
               def matcher_for(value, format_for_presentation)
                 # Nokogiri doesn't like arbitrary values without quotes, hence inspect.
-                if format_for_presentation || value.is_a?(String)
+                if format_for_presentation
                   value.inspect # Avoid to_s so Regexps aren't put in quotes.
-                else
+                elsif value.is_a?(Regexp)
                   "\"#{value}\""
+                else
+                  value.to_s.inspect
                 end
               end