move csslib into dart svn

pkg/csslib/README.md

+csslib in Pure Dart
+===================
+
+This is a pure [Dart][dart] [CSS parser][cssparse]. Since it's 100%
+Dart you can use it safely from a script or server side app.
+
+[![Build Status](https://drone.io/github.com/dart-lang/csslib/status.png)](https://drone.io/github.com/dart-lang/csslib/latest)
+
+Installation
+------------
+
+Add this to your `pubspec.yaml` (or create it):
+```yaml
+dependencies:
+  csslib: any
+```
+Then run the [Pub Package Manager][pub] (comes with the Dart SDK):
+
+    pub install
+
+Usage
+-----
+
+Parsing CSS is easy!
+```dart
+import 'package:csslib/parser.dart' show parse;
+import 'package:csslib/css.dart';
+
+main() {
+  var stylesheet = parse(
+      '.foo { color: red; left: 20px; top: 20px; width: 100px; height:200px }');
+  print(stylesheet.toString());
+}
+```
+
+You can pass a String or list of bytes to `parse`.
+
+
+Updating
+--------
+
+You can upgrade the library with:
+
+    pub update
+
+Disclaimer: the APIs are not finished. Updating may break your code. If that
+happens, you can check the
+[commit log](https://github.com/dart-lang/csslib/commits/master), to figure
+out what the change was.
+
+If you want to avoid breakage, you can also put the version constraint in your
+`pubspec.yaml` in place of the word `any`.
+
+Running Tests
+-------------
+
+All tests (both canary and suite) should be passing.  Canary are quick test
+verifies that basic CSS is working.  The suite tests are a comprehensive set of
+~11,000 tests.
+
+```bash
+export DART_SDK=path/to/dart/sdk
+
+# Make sure dependencies are installed
+pub install
+
+# Run command both canary and the suite tests
+test/run.sh
+```
+
+  Run only the canary test:
+
+```bash
+ test/run.sh canary
+```
+
+  Run only the suite tests:
+
+```bash
+ test/run.sh suite
+```
+
+[dart]: http://www.dartlang.org/
+[pub]: http://www.dartlang.org/docs/pub-package-manager/