Added test case

Author: JasonH53

tests/init-global/pos-tasty/test-safe-value.scala

@@ -0,0 +1,7 @@
+package scala.collection.immutable
+
+object A { // These are a safe values, so no warning should be emitted
+    Node.HashCodeLength 
+    Node.BitPartitionSize
+    Node.MaxDepth 
+}