Index: includes/theme.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/theme.inc,v
retrieving revision 1.593
diff -u -p -r1.593 theme.inc
--- includes/theme.inc	26 Apr 2010 17:54:49 -0000	1.593
+++ includes/theme.inc	27 Apr 2010 22:43:13 -0000
@@ -1903,6 +1903,11 @@ function theme_feed_icon($variables) {
 /**
  * Returns HTML for a generic HTML tag with attributes.
  *
+ * This theme function may be used for tags appearing in the HTML HEAD of a
+ * document (specified via the #tag property in the passed $element). It is not
+ * recommended to use this theme function for tags appearing elsewhere, since
+ * more specific theme functions should be used for anything visible.
+ *
  * @param $variables
  *   An associative array containing:
  *   - element: An associative array describing the tag:
@@ -1917,24 +1922,34 @@ function theme_feed_icon($variables) {
  *       wrapper prefix.
  *     - #value_suffix: (optional) A string to append to #value, e.g. a CDATA
  *       wrapper suffix.
+ *     - #empty: (optional) Can be set to TRUE or FALSE to force the rendered
+ *       output to use the minimized tag syntax (e.g., "<meta ... />") or not
+ *       (e.g., "<script ...></script>") if its content is empty. Defaults to
+ *       the XHTML guidelines (http://www.w3.org/TR/xhtml1/#guidelines).
  */
 function theme_html_tag($variables) {
+  // @see http://www.w3.org/TR/xhtml1/dtds.html
+  static $empty_tags = array('area', 'base', 'basefont', 'br', 'col', 'hr', 'img', 'input', 'isindex', 'link', 'meta', 'param');
   $element = $variables['element'];
-  if (!isset($element['#value'])) {
-    return '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . " />\n";
-  }
-  else {
-    $output = '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . '>';
+
+  $minimize = isset($element['#empty']) ? $element['#empty'] : in_array(strtolower($element['#tag']), $empty_tags);
+  $content = '';
+  if (isset($element['#value'])) {
     if (isset($element['#value_prefix'])) {
-      $output .= $element['#value_prefix'];
+      $content .= $element['#value_prefix'];
     }
-    $output .= $element['#value'];
+    $content .= $element['#value'];
     if (isset($element['#value_suffix'])) {
-      $output .= $element['#value_suffix'];
+      $content .= $element['#value_suffix'];
     }
-    $output .= '</' . $element['#tag'] . ">\n";
-    return $output;
   }
+  if ($minimize && !drupal_strlen($content)) {
+    $output = '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . " />\n";
+  }
+  else {
+    $output = '<' . $element['#tag'] . drupal_attributes($element['#attributes']) . '>' . $content . '</' . $element['#tag'] . ">\n";
+  }
+  return $output;
 }
 
 /**