Index: includes/common.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/common.inc,v
retrieving revision 1.611.2.26
diff -u -p -r1.611.2.26 common.inc
--- includes/common.inc	4 Mar 2010 00:16:02 -0000	1.611.2.26
+++ includes/common.inc	21 Jun 2010 05:51:02 -0000
@@ -1685,11 +1685,21 @@ function drupal_build_css_cache($types, 
     $data = implode('', $matches[0]) . $data;
 
     // Perform some safe CSS optimizations.
-    $data = preg_replace('<
-      \s*([@{}:;,]|\)\s|\s\()\s* |  # Remove whitespace around separators, but keep space around parentheses.
-      /\*([^*\\\\]|\*(?!/))+\*/ |   # Remove comments that are not CSS hacks.
-      [\n\r]                        # Remove line breaks.
-      >x', '\1', $data);
+    // Regexp to match comment blocks.
+    $comment     = '/\*[^*]*\*+(?:[^/*][^*]*\*+)*/';
+    // Regexp to match double quoted strings.
+    $double_quot = '"[^"\\\\]*(?:\\\\.[^"\\\\]*)*"';
+    // Regexp to match single quoted strings.
+    $single_quot = "'[^'\\\\]*(?:\\\\.[^'\\\\]*)*'";
+    $data = preg_replace_callback(
+      "<$double_quot|$single_quot|$comment>Sus",  // Match all comment blocks along
+      "_process_comment",                         // with double/single quoted strings
+      $data);                                     // and feed them to _process_comment().
+    $data = preg_replace(
+      '<\s*([@{}:;,]|\)\s|\s\()\s*>S',            // Remove whitespace around separators,
+      '\1', $data);                               // but keep space around parentheses.
+    // End the file with a new line.
+    $data .= "\n";
 
     // Create the CSS file.
     file_save_data($data, $csspath .'/'. $filename, FILE_EXISTS_REPLACE);
@@ -1698,6 +1708,41 @@ function drupal_build_css_cache($types, 
 }
 
 /**
+ * Process comment blocks.
+ *
+ * This is the callback function for the preg_replace_callback()
+ * used in drupal_load_stylesheet_content(). Support for comment
+ * hacks is implemented here.
+ */
+function _process_comment($matches) {
+  static $keep_nextone = FALSE;
+
+  // Quoted string, keep it.
+  if ($matches[0][0] == "'" || $matches[0][0] == '"') {
+    return $matches[0];
+  }
+  // End of IE-Mac hack, keep it.
+  if ($keep_nextone) {
+    $keep_nextone = FALSE;
+    return $matches[0];
+  }
+  switch (strrpos($matches[0], '\\')) {
+    case FALSE :
+      // No backslash, strip it.
+      return '';
+
+    case drupal_strlen($matches[0])-3 :
+      // Ends with \*/ so is a multi line IE-Mac hack, keep the next one also.
+      $keep_nextone = TRUE;
+      return '/*_\*/';
+
+    default :
+      // Single line IE-Mac hack.
+      return '/*\_*/';
+  }
+}
+
+/**
  * Delete all cached CSS files.
  */
 function drupal_clear_css_cache() {