Delete polymer from the Dart repo

pkg/polymer/test/instance_attrs_test.dart

-// Copyright (c) 2013, 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.
-
-import 'dart:html';
-import 'package:unittest/unittest.dart';
-import 'package:unittest/html_config.dart';
-import 'package:polymer/polymer.dart';
-
-// Note: we use @CustomTag to make this type reflectable.
-@CustomTag('my-element')
-class MyElement extends PolymerElement {
-  MyElement.created() : super.created();
-
-  // This is here so that [attributes] can be read via mirrors in polymer
-  // expressions (@CustomTag in this class makes the attribute reflectable).
-  get attributes => super.attributes;
-}
-
-main() => initPolymer().run(() {
-  useHtmlConfiguration();
-
-  setUp(() => Polymer.onReady);
-
-  test('attributes were deserialized', () {
-    var elem = querySelector('my-element');
-
-    expect(elem.attributes, {'foo': '123', 'bar': 'hi', 'baz': 'world'},
-        reason: 'attributes should be copied to instance');
-
-    var text = elem.shadowRoot.text;
-    // Collapse adjacent whitespace like a browser would:
-    text = text.replaceAll('\n', ' ').replaceAll(new RegExp(r'\s+'), ' ');
-
-    expect(text, " foo: 123 bar: hi baz: world ",
-        reason: 'text should match expected HTML template');
-  });
-});