Mark lib/async/slow_consumer2_test as failing on noopt + simarm64.

tests/lib/lib.status

Index: tests/lib/lib.status
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index d854ac9c2c0f8c97b9765a0601f12afb4185ea0e..317880e05ec24eab1ed48bafe3f95ae323c143d6 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -348,6 +348,9 @@ mirrors/typedef_library_test: Crash # Assertion failure: typedef(G) has not been
 [ $compiler != dart2js ]
 async/dart2js_uncaught_error_test: Skip  # JS-integration only test
 
+[ $noopt && $arch == simarm64 ]
+async/slow_consumer2_test: Pass, RuntimeError # Issue 25726
+
 [ ($noopt || $compiler == precompiler) ]
 mirrors/*: SkipByDesign
 convert/chunked_conversion_utf88_test: Pass, Timeout