Fix test to return expected value.

bug:28335959
Change-Id: Id4b3fc7b3ea5705530283daffedef17ab0699ae9
diff --git a/test/570-checker-osr/src/Main.java b/test/570-checker-osr/src/Main.java
index 11a6fd4..15c232d 100644
--- a/test/570-checker-osr/src/Main.java
+++ b/test/570-checker-osr/src/Main.java
@@ -192,7 +192,7 @@
     // If we are running in non-JIT mode, or were unlucky enough to get this method
     // already JITted, just return the expected value.
     if (!isInInterpreter("$noinline$inlineCache3")) {
-      return SubMain.class;
+      return null;
     }
 
     ensureHasProfilingInfo("$noinline$inlineCache3");