escape_once uses negative lookahead to avoid double-escaping instead of a second gsub

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7606 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

actionpack/lib/action_view/helpers/tag_helper.rb

@@ -94,7 +94,7 @@ def cdata_section(content)
       #   escape_once("<< Accept & Checkout")
       #   # => "<< Accept & Checkout"
       def escape_once(html)
-        fix_double_escape(html_escape(html.to_s))
+        html.to_s.gsub(/[\"><]|&(?!([a-zA-Z]+|(#\d+));)/) { |special| ERB::Util::HTML_ESCAPE[special] }
       end
 
       private
@@ -116,11 +116,6 @@ def tag_options(options)
           end
         end
 
-        # Fix double-escaped entities, such as &amp;amp;, &amp;#123;, etc.
-        def fix_double_escape(escaped)
-          escaped.gsub(/&amp;([a-z]+|(#\d+));/i) { "&#{$1};" }
-        end
-
         def block_is_within_action_view?(block)
           eval("defined? _erbout", block.binding)
         end