Fix tests for VM in checked mode.

pkg/http/test/http_test.dart

 // Copyright (c) 2012, 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.
 
 library http_test;
 
 import 'dart:io';
 
 import 'package:unittest/unittest.dart';
 import 'package:http/http.dart' as http;
 import 'utils.dart';
 
 main() {
   group('http.', () {
     setUp(startServer);
     tearDown(stopServer);
 
     test('head', () {
-      expect(http.head(serverUrl).then(expectAsync1((response) {
+      http.head(serverUrl).then(expectAsync1((response) {
         expect(response.statusCode, equals(200));
         expect(response.body, equals(''));
-      })), completes);
+      }));
     });
 
     test('get', () {
       expect(http.get(serverUrl, headers: {
         'X-Random-Header': 'Value',
         'X-Other-Header': 'Other Value'
       }).then(expectAsync1((response) {
         expect(response.statusCode, equals(200));
         expect(response.body, parse(equals({
           'method': 'GET',
@@ skipping 122 matching lines @@
       }).then(expectAsync1((val) => val)), completion(parse(equals({
         'method': 'GET',
         'path': '/',
         'headers': {
           'content-length': ['0'],
           'x-random-header': ['Value'],
           'x-other-header': ['Other Value']
         },
       }))));
     });
-    
+
     test('read throws an error for a 4** status code', () {
-      expect(http.read(serverUrl.resolve('/error')).then((expectAsync1(x) => x)),
-             throwsHttpException);
+      http.read(serverUrl.resolve('/error')).catchError(expectAsync1((e) {
+        expect(true, e.error is HttpException);
+      }));
     });
-    
+
     test('readBytes', () {
       var future = http.readBytes(serverUrl, headers: {
         'X-Random-Header': 'Value',
         'X-Other-Header': 'Other Value'
       }).then(expectAsync1((bytes) => new String.fromCharCodes(bytes)));
 
       expect(future, completion(parse(equals({
         'method': 'GET',
         'path': '/',
         'headers': {
           'content-length': ['0'],
           'x-random-header': ['Value'],
           'x-other-header': ['Other Value']
         },
       }))));
     });
 
     test('readBytes throws an error for a 4** status code', () {
-      expect(http.readBytes(serverUrl.resolve('/error')).then((expectAsync1(x) => x)),
-             throwsHttpException);
+      http.readBytes(serverUrl.resolve('/error')).catchError(expectAsync1((e) {
+        expect(true, e.error is HttpException);
+      }));
     });
   });
 }