Remove deprecated StringBuffer.add, addAll and addCharCode.

utils/css/uitest.dart

Index: utils/css/uitest.dart
diff --git a/utils/css/uitest.dart b/utils/css/uitest.dart
index 87c913adcc5c9645647a1a18a42001ef6b3b78bb..bbbbad0a15084dd4792d489897a7241a79547f6a 100644
--- a/utils/css/uitest.dart
+++ b/utils/css/uitest.dart
@@ -43,9 +43,9 @@ void runCss([bool debug = false, bool parseOnly = false]) {
       Stylesheet stylesheet = parser.parse();
       StringBuffer stylesheetTree = new StringBuffer();
       String prettyStylesheet = stylesheet.toString();
-      stylesheetTree.add("${prettyStylesheet}\n");
-      stylesheetTree.add("\n============>Tree Dump<============\n");
-      stylesheetTree.add(stylesheet.toDebugString());
+      stylesheetTree.write("${prettyStylesheet}\n");
+      stylesheetTree.write("\n============>Tree Dump<============\n");
+      stylesheetTree.write(stylesheet.toDebugString());
       dumpTree = stylesheetTree.toString();
     } catch (cssParseException) {
       templateValid = false;