Rip out the last dart:io dependency from pkg/http.

pkg/http/test/html/streamed_request_test.dart

+// Copyright (c) 2014, 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.html.streamed_request_test;
+
+import 'dart:convert';
+
+import 'package:http/http.dart' as http;
+import 'package:http/browser_client.dart';
+import 'package:unittest/unittest.dart';
+
+import 'utils.dart';
+
+void main() {
+  group('contentLength', () {
+    test("works when it's set", () {
+      var request = new http.StreamedRequest('POST', echoUrl);
+      request.contentLength = 10;
+      request.sink.add([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+      request.sink.close();
+
+      return new BrowserClient().send(request).then((response) {
+        expect(response.stream.toBytes(),
+            completion(equals([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])));
+      });
+    });
+
+    test("works when it's not set", () {
+      var request = new http.StreamedRequest('POST', echoUrl);
+      request.sink.add([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]);
+      request.sink.close();
+
+      return new BrowserClient().send(request).then((response) {
+        expect(response.stream.toBytes(),
+            completion(equals([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])));
+      });
+    });
+  });
+}