Stop using i18n's built in HTML error handling.

i18n doesn't depend on active support which means it can't use our html_safe
code to do its escaping when generating the spans.  Rather than try to sanitize
the output from i18n, just revert to our old behaviour of rescuing the error
and constructing the tag ourselves.

Fixes: CVE-2013-4491

Conflicts:
	actionpack/lib/action_view/helpers/translation_helper.rb

Backport: 50afd8eec9d088ad5a2d41f00a05520d5b78a6a0

actionpack/lib/action_view/helpers/translation_helper.rb

@@ -1,24 +1,14 @@
 require 'action_view/helpers/tag_helper'
 require 'i18n/exceptions'
 
-module I18n
-  class ExceptionHandler
-    include Module.new {
-      def call(exception, locale, key, options)
-        exception.is_a?(MissingTranslation) && options[:rescue_format] == :html ? super.html_safe : super
-      end
-    }
-  end
-end
-
 module ActionView
   # = Action View Translation Helpers
   module Helpers
     module TranslationHelper
       # Delegates to <tt>I18n#translate</tt> but also performs three additional functions.
       #
-      # First, it'll pass the <tt>:rescue_format => :html</tt> option to I18n so that any
-      # thrown +MissingTranslation+ messages will be turned into inline spans that
+      # First, it will ensure that any thrown +MissingTranslation+ messages will be turned 
+      # into inline spans that:
       #
       #   * have a "translation-missing" class set,
       #   * contain the missing key as a title attribute and
@@ -44,7 +34,9 @@ module ActionView
       # naming convention helps to identify translations that include HTML tags so that
       # you know what kind of output to expect when you call translate in a template.
       def translate(key, options = {})
-        options.merge!(:rescue_format => :html) unless options.key?(:rescue_format)
+        # If the user has specified rescue_format then pass it all through, otherwise use
+        # raise and do the work ourselves
+        options[:raise] = true unless options.key?(:raise) || options.key?(:rescue_format)
         if html_safe_translation_key?(key)
           html_safe_options = options.dup
           options.except(*I18n::RESERVED_KEYS).each do |name, value|
@@ -58,6 +50,9 @@ module ActionView
         else
           I18n.translate(scope_key_by_partial(key), options)
         end
+      rescue I18n::MissingTranslationData => e
+        keys = I18n.normalize_keys(e.locale, e.key, e.options[:scope])
+        content_tag('span', keys.last.to_s.titleize, :class => 'translation_missing', :title => "translation missing: #{keys.join('.')}")
       end
       alias :t :translate
 

actionpack/test/template/translation_helper_test.rb

@@ -30,7 +30,7 @@ class TranslationHelperTest < ActiveSupport::TestCase
   end
 
   def test_delegates_to_i18n_setting_the_rescue_format_option_to_html
-    I18n.expects(:translate).with(:foo, :locale => 'en', :rescue_format => :html).returns("")
+    I18n.expects(:translate).with(:foo, :locale => 'en', :raise=>true).returns("")
     translate :foo, :locale => 'en'
   end