Beginning of CSS parser using frog parsering infrastructure.

utils/css/cssworld.dart

Index: utils/css/cssworld.dart
diff --git a/utils/css/cssworld.dart b/utils/css/cssworld.dart
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+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class CssWorld {
+  List<String> classes;
+  List<String> ids;
+
+  CssWorld(this.classes, this.ids) {
+    // Insure no private class names in our CSS world (._foo).
+    for (aClass in classes) {
+      if (aClass.startsWith('_')) {
+        throw new CssSelectorException(
+            "private class ('_' prefix) not valid for CssWorld $aClass)");
+      }
+    }
+
+    // Insure no private element ids in our CSS world (#_foo).
+    for (id in ids) {
+      if (id.startsWith('_')) {
+        throw new CssSelectorException(
+            "private id ('_' prefix) not valid for CssWorld $id)");
+      }
+    }
+  }
+}