fixes #221, initial sync*, async, async* implementation

test/browser/minitest.dart

-// Copyright (c) 2015, 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.
-
-// TODO(jmesserly): replace this with the real package:test.
-// Not possible yet because it uses on async/await which we don't support.
-library minitest;
-
-import 'dom.dart';
-
-final console = (window as dynamic).console;
-
-void group(String name, void body()) {
-  console.group(name);
-  body();
-  console.groupEnd(name);
-}
-
-void test(String name, void body(), {String skip}) {
-  if (skip != null) {
-    console.warn('SKIP $name: $skip');
-    return;
-  }
-  console.log(name);
-  try {
-    body();
-  } catch(e) {
-    console.error(e);
-  }
-}
-
-void expect(Object actual, matcher) {
-  if (matcher is! Matcher) matcher = equals(matcher);
-  if (!matcher(actual)) {
-    throw 'Expect failed to match $actual with $matcher';
-  }
-}
-
-Matcher equals(Object expected) {
-  return (actual) {
-    if (expected is List && actual is List) {
-      int len = expected.length;
-      if (len != actual.length) return false;
-      for (int i = 0; i < len; i++) {
-        if (!equals(expected[i])(actual[i])) return false;
-      }
-      return true;
-    } else {
-      return expected == actual;
-    }
-  };
-}
-
-Matcher same(Object expected) => (actual) => identical(expected, actual);
-Matcher isNot(matcher) {
-  if (matcher is! Matcher) matcher = equals(matcher);
-  return (actual) => !matcher(actual);
-}
-
-bool isNull(actual) => actual == null;
-final Matcher isNotNull = isNot(isNull);
-bool isRangeError(actual) => actual is RangeError;
-bool isNoSuchMethodError(actual) => actual is NoSuchMethodError;
-
-Matcher throwsA(matcher) {
-  if (matcher is! Matcher) matcher = equals(matcher);
-  return (actual) {
-    try {
-      actual();
-      return false;
-    } catch(e) {
-      return matcher(e);
-    }
-  };
-}
-
-final Matcher throws = throwsA((a) => true);
-
-typedef Matcher(actual);