Limit pub to 16 concurrent HTTP requests.

sdk/lib/_internal/pub/test/test_pub.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.
 
 /// Test infrastructure for testing pub.
 ///
 /// Unlike typical unit tests, most pub tests are integration tests that stage
 /// some stuff on the file system, run pub, and then validate the results. This
 /// library provides an API to build tests like that.
 library test_pub;
@@ skipping 817 matching lines @@
   }
 
   return lockFile;
 }
 
 /// Uses [client] as the mock HTTP client for this test.
 ///
 /// Note that this will only affect HTTP requests made via http.dart in the
 /// parent process.
 void useMockClient(MockClient client) {
-  var oldInnerClient = httpClient.inner;
-  httpClient.inner = client;
+  var oldInnerClient = innerHttpClient;
+  innerHttpClient = client;
   currentSchedule.onComplete.schedule(() {
-    httpClient.inner = oldInnerClient;
+    innerHttpClient = oldInnerClient;
   }, 'de-activating the mock client');
 }
 
 /// Describes a map representing a library package with the given [name],
 /// [version], and [dependencies].
 Map packageMap(String name, String version, [Map dependencies]) {
   var package = {
     "name": name,
     "version": version,
     "author": "Nathan Weizenbaum <nweiz@google.com>",
@@ skipping 160 matching lines @@
         _lastMatcher.matches(item.last, matchState);
   }
 
   Description describe(Description description) {
     return description.addAll("(", ", ", ")", [_firstMatcher, _lastMatcher]);
   }
 }
 
 /// A [StreamMatcher] that matches multiple lines of output.
 StreamMatcher emitsLines(String output) => inOrder(output.split("\n"));