Limit pub to 16 concurrent HTTP requests.

sdk/lib/_internal/pub/test/test_pub.dart

Index: sdk/lib/_internal/pub/test/test_pub.dart
diff --git a/sdk/lib/_internal/pub/test/test_pub.dart b/sdk/lib/_internal/pub/test/test_pub.dart
index 1bbf30716558b80ec23a70b3ae1d5ec1a4d758f2..6729e0d3b25317894c82083966ac3de1b98351b3 100644
--- a/sdk/lib/_internal/pub/test/test_pub.dart
+++ b/sdk/lib/_internal/pub/test/test_pub.dart
@@ -835,10 +835,10 @@ Iterable<String> pkg, Map<String, String> hosted}) {
 /// 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');
 }