Mark more service tests as flaky.

TBR'ed.

R=johnmccutchan@google.com
BUG=

Review-Url: https://codereview.chromium.org/2597983002 .

runtime/observatory/tests/service/service.status

@@ -8,9 +8,11 @@ gc_test: Pass, RuntimeError # Issue 26490
 pause_on_start_and_exit_test: Pass, RuntimeError # Issue 26470
 pause_on_start_then_step_test: Pass, RuntimeError # Issue 26470
 get_allocation_samples_test: Pass, RuntimeError # Inconsistent stack trace
+get_isolate_rpc_test: Pass, RuntimeError # Issue 28185
 set_library_debuggable_test: Pass, RuntimeError # Issue 28091
-# Reload is slow on the bots
-reload_sources_test: Pass, Slow
+reload_sources_test: Pass, Slow # Reload is slow on the bots
+rewind_test: Pass, RuntimeError # Issue 28047
+tcp_socket_service_test: Pass, RuntimeError # Issue 28184
 
 [ ($compiler == none || $compiler == precompiler) && ($runtime == vm || $runtime == dart_precompiled) ]
 evaluate_activation_test/instance: RuntimeError # http://dartbug.com/20047
@@ -79,7 +81,6 @@ rewind_optimized_out_test: RuntimeError # Issue 27878
 dev_fs_weird_char_test: Skip # Windows disallows question mark in paths
 dev_fs_http_put_weird_char_test: Skip # Windows disallows carriage returns in paths
 complex_reload_test: Skip # Issue 27861
-rewind_test: Pass, RuntimeError # Issue 28047
 
 # Service protocol is not supported in product mode.
 [ $mode == product ]