commit f048f6b334d402908f69ed74dc0650294aded367
Author: Shane Auckland <shane.auckland@gmail.com>
Date:   Thu May 9 18:02:20 2013 +0100

    rerolling

diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index 0d0e739..dc9fb35 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2686,9 +2686,6 @@ function template_preprocess(&$variables, $hook) {
     'title_attributes' => array(),
     'content_attributes' => array(),
   );
-
-  // Initialize html class attribute for the current hook.
-  $variables['attributes']['class'][] = drupal_html_class($hook);
 }
 
 /**
@@ -3169,6 +3166,7 @@ function template_preprocess_region(&$variables) {
   $variables['content'] = $variables['elements']['#children'];
   $variables['region'] = $variables['elements']['#region'];
 
+  $variables['attributes']['class'][] = 'region';
   $variables['attributes']['class'][] = drupal_region_class($variables['region']);
   $variables['theme_hook_suggestions'][] = 'region__' . $variables['region'];
 }
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index 57f1572..8d15422 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -545,6 +545,7 @@ function template_preprocess_block(&$variables) {
   // Create the $content variable that templates expect.
   $variables['content'] = $variables['elements']['#children'];
 
+  $variables['attributes']['class'][] = 'block';
   $variables['attributes']['class'][] = drupal_html_class('block-' . $variables['block']->module);
 
   // Add default class for block content.
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index 6d0d003..b9208a1 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -1646,6 +1646,7 @@ function template_preprocess_comment(&$variables) {
   }
 
   // Gather comment classes.
+  $variables['attributes']['class'][] = 'comment';
   // 'published' class is not needed, it is either 'preview' or 'unpublished'.
   if ($variables['status'] != 'published') {
     $variables['attributes']['class'][] = $variables['status'];