Improve the handling of HTTP requests with empty body

tests/standalone/standalone.status

 # 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.
 
 package/invalid_uri_test: Fail, OK # Fails intentionally
 
 [ $runtime == vm && $checked ]
 # These tests have type errors on purpose.
 io/process_invalid_arguments_test: Fail, OK
 io/directory_invalid_arguments_test: Fail, OK
 io/file_invalid_arguments_test: Fail, OK
 io/socket_invalid_arguments_test: Fail, OK
 # These test have type errors on purpose and take very long to run in
 # checked mode with no benefit. Skip.
 io/file_fuzz_test: Skip
 io/directory_fuzz_test: Skip
 
 [ $runtime == vm && $system == linux ]
 io/test_runner_test: Pass, Fail  # Issue 1947
 
 [ $runtime == vm && $system == macos ]
 # This test fails with "Too many open files" on the Mac OS buildbot.
 # This is expected as MacOS by default runs with a very low number
 # of allowed open files ('ulimit -n' says something like 256).
 io/socket_many_connections_test: Skip
-io/http_auth_test: Skip  # Issue 7183
 
 # These tests pass on MacOS 10.8.2 but fails on the buildbot machines
 # that are running an earlier version of MacOS. The issue is that the
 # old version of MacOS does not expand the precomposed utf-8 it gets
 # from the VM before comparing it to the decomposed utf-8 used for the
 # file system.
 io/file_non_ascii_sync_test: Pass, Fail
 io/file_non_ascii_test: Pass, Fail
 io/directory_non_ascii_sync_test: Pass, Fail
 io/directory_non_ascii_test: Pass, Fail
@@ skipping 49 matching lines @@
 [ $compiler == dart2js && $browser ]
 *: Skip
 
 [ $compiler == dart2js && $checked ]
 io/http_read_test: Skip # Timeout TODO(ngeoffray): investigate
 io/list_input_stream_test: Skip # Timeout TODO(ngeoffray): investigate
 
 [ $compiler == dart2dart ]
 # Skip until we stabilize language tests.
 *: Skip