Do not do a type check when setting null to an array.

Change-Id: I7387d45aea697d4a3de273335647220a815a992b
diff --git a/test/521-checker-array-set-null/info.txt b/test/521-checker-array-set-null/info.txt
new file mode 100644
index 0000000..ec2ba35
--- /dev/null
+++ b/test/521-checker-array-set-null/info.txt
@@ -0,0 +1,2 @@
+Checker test for optimizing that checks whether our
+optimizations to remove type checks on array set operations work.