fixes a couple of regexps, the suite showed warnings about them

A couple of things worth mentioning here:

 - "{" is a metacharacter, should be escaped
   if it is meant to match a "{". The code
   worked, though, because the regexp engine
   is tolerant to this, but issued warnings.

 - gsub accepts a string as first argument.
   That's the best idiom to use when your
   pattern has no metacharacters, since gsub
   interprets the string as an exact substring
   to look for, rather than a regexp. The
   benefit is that your pattern is crystal
   clear and needs no backslashes.

actionpack/lib/action_view/template/resolver.rb

@@ -157,8 +157,8 @@ def build_query(path, exts)
         query.gsub!(/\:#{ext}/, "{#{variants.compact.uniq.join(',')}}")
       }
 
-      query.gsub!(/\.{html,/, ".{html,text.html,")
-      query.gsub!(/\.{text,/, ".{text,text.plain,")
+      query.gsub!('.{html,', '.{html,text.html,')
+      query.gsub!('.{text,', '.{text,text.plain,')
 
       File.expand_path(query, @path)
     end