Mark precompilation_dart2js_test as Pass, Slow in debug mode.

tests/standalone/standalone.status

 # 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.
 
 # WARNING:
 # Tests using the multitest feature where failure is expected should *also* be
 # listed in tests/lib/analyzer/analyze_tests.status without the "standalone"
 # prefix.
 
 package/invalid_uri_test: Fail, OK # CompileTimeErrors intentionally
@@ skipping 93 matching lines @@
 issue14236_test: Skip # dart2js does not deal with Script snapshots.
 javascript_compatibility_errors_test: Skip
 javascript_compatibility_warnings_test: Skip
 unboxed_int_converter_test: Skip
 pair_location_remapping_test: Skip
 precompilation_test: Skip # Standalone only test.
 precompilation_dart2js_test: Skip # Standalone only test.
 noopt_test: Skip # Standalone only test.
 
 [ $runtime == vm && $mode == debug ]
-precompilation_dart2js_test: Slow
+precompilation_dart2js_test: Pass, Slow
 
 [ $runtime == vm && $arch == ia32 ]
 precompilation_test: Skip # Not expected to pass on ia32.
 precompilation_dart2js_test: Skip # Not expected to pass on ia32.
 noopt_test: Skip # Not expected to pass on ia32.
 
 [ $runtime == vm && $arch == arm ]
 precompilation_test: Skip # Issue 24427
 precompilation_dart2js_test: Skip # Issue 24427
 
@@ skipping 92 matching lines @@
 [ $runtime == vm ]
 # Failures in secure networking while NSS is replaced with BoringSSL
 io/https_client_certificate_test: RuntimeError # Issue 24070
 io/secure_socket_renegotiate_test: RuntimeError
 io/secure_socket_bad_data_test: RuntimeError  # An error in a secure connection just puts a READ_CLOSED on the stream, rather than signaling an error on the stream.
 
 [ $noopt ]
 map_literal_oom_test: Pass, Crash # Issue 24678
 javascript*: SkipByDesign # JS overflow flag unsupported
 io/web_socket_test: Pass, RuntimeError # Issue 24674