Add 2254-class-value test to knownfailures.json.

This test relies on dalvik.system.VMRuntime and should not be run
on JVM.

Bug: 32299208
Test: art/test.py -b --host -r
Change-Id: Icd566df767ce854d6a398f4c48104c8893d5c348
diff --git a/test/knownfailures.json b/test/knownfailures.json
index 5f79b21..44ba3e9 100644
--- a/test/knownfailures.json
+++ b/test/knownfailures.json
@@ -1217,7 +1217,8 @@
                   "2040-huge-native-alloc",
                   "2238-checker-polymorphic-recursive-inlining",
                   "2240-tracing-non-invokable-method",
-	          "2246-trace-stream"],
+                  "2246-trace-stream",
+                  "2254-class-value-before-and-after-u"],
         "variant": "jvm",
         "description": ["Doesn't run on RI."]
     },