Change IllegalArgumentException to ArgumentError.

runtime/bin/http_impl.dart

Index: runtime/bin/http_impl.dart
diff --git a/runtime/bin/http_impl.dart b/runtime/bin/http_impl.dart
index ecebe4c243e7c33245022dbc15be1afa23a59d52..cb1776857fae395e14ea7648fa7a523e16b351c1 100644
--- a/runtime/bin/http_impl.dart
+++ b/runtime/bin/http_impl.dart
@@ -1968,7 +1968,7 @@ class _HttpClient implements HttpClient {
                              [_HttpClientConnection connection]) {
     if (_shutdown) throw new HttpException("HttpClient shutdown");
     if (method == null || host == null || port == null || path == null) {
-      throw new IllegalArgumentException(null);
+      throw new ArgumentError(null);
     }
     return _prepareHttpClientConnection(host, port, method, path, connection);
   }