Skip utf85_test on simarm64 because it timesout

tests/lib/lib.status

Index: tests/lib/lib.status
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index ff99e8df807dfa30a7f15eda2b766ae31e7fe960..687e9ab0fb11ac96eb40b68e62870dcf874988b9 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -319,6 +319,9 @@ convert/streamed_conversion_json_utf8_decode_test: Skip  # Pass, Slow
 convert/chunked_conversion_utf88_test: Skip  # Pass, Slow Issue 12644.
 convert/utf85_test: Skip  # Pass, Slow Issue 12644.
 
+[ $arch == simarm64 ]
+convert/utf85_test: Skip # Pass, Slow Issue 20111.
+
 # These tests use "const Symbol('void')".
 [ $compiler == dartanalyzer || $compiler == dart2analyzer ]
 mirrors/basic_types_in_dart_core_test: CompileTimeError