Update status for failing tests

tests/lib/lib.status

Index: tests/lib/lib.status
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index 6be0ee903c742ff9178339312ae1ff476ed30d8c..f4114a2bf09136a569e58c10db5e1a0d248426b0 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -279,6 +279,9 @@ mirrors/spawn_function_root_library_test: SkipByDesign # Uses spawnFunction.
 mirrors/local_isolate_test: RuntimeError # Issue 12188
 mirrors/deferred_type_test: RuntimeError, OK # Should be CompileTimeError. Issue 22072
 
+[ $compiler == none && $runtime == dartium && $system == macos ]
+convert/streamed_conversion_utf8_decode_test: Pass, Slow
+
 [ $compiler == none && $runtime == drt && $system == windows ]
 async/multiple_timer_test: Fail, Pass # See Issue 10982
 async/timer_test: Fail, Pass # See Issue 10982