Reenable a few previously slow tests on MIPS.

tests/lib/lib.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.
 
 [ $unchecked ]
 mirrors/redirecting_factory_different_type_test: SkipByDesign # Tests type checks.
 
 [ $csp ]
 # Deferred loading does not work from an isolate in CSP-mode
 async/deferred/deferred_in_isolate_test: Skip # Issue 16898
@@ skipping 285 matching lines @@
 [ ($compiler == dartanalyzer || $compiler == dart2analyzer) && $checked ]
 mirrors/regress_16321_test/01: MissingCompileTimeError # Issue 16391
 
 [ $compiler == dart2js && $runtime == d8 && $system == windows ]
 async/*deferred*: Skip # Issue 17458
 mirrors/*deferred*: Skip # Issue 17458
 
 [ $compiler == dart2js && $mode == debug ]
 mirrors/native_class_test: Pass, Slow
 
-[ $arch == simmips || $arch == mips ]
-convert/chunked_conversion_utf88_test: Skip  # Pass, Slow Issue 12025.
-convert/streamed_conversion_json_utf8_decode_test: Skip  # Pass, Slow
-
 [ $arch == simarm ]
 convert/chunked_conversion_utf88_test: Skip  # Pass, Slow Issue 12644.
 convert/utf85_test: Skip  # Pass, Slow Issue 12644.
 
 [ $compiler == dart2js ]
 profiler/metrics_num_test: Skip # Because of a int / double type test.
 
 [ $arch == simarm64 ]
 convert/utf85_test: Skip # Pass, Slow Issue 20111.
 
 [ $mode == debug && $arch == ia32 && $system == windows ]
 convert/streamed_conversion_json_utf8_decode_test: Skip  # Verification OOM.
 
 [ $mode == debug && $arch != ia32 && $arch != x64 ]
 convert/streamed_conversion_json_utf8_decode_test: Skip  # Verification not yet implemented.