debugging tweak

Author: mikesamuel

tests/prettify_test.html

@@ -761,6 +761,12 @@ <h1>HTML using XMP</h1>
       });
     var actual = normalizedInnerHtml(document.getElementById(lang));
     if (golden !== actual) {  // test failed
+      pre = pre.replace(/\\/g, '\\\\')
+               .replace(/\r/g, '\\r')
+               .replace(/\n/g, '\\n\n');
+      post = post.replace(/\\/g, '\\\\')
+               .replace(/\r/g, '\\r')
+               .replace(/\n/g, '\\n\n');
       // write out
       var pre = commonPrefix(golden, actual);
       var post = commonSuffix(golden, actual, pre);