Temporarily revert "more check for casts"

(because commit broke seveal tests)

This reverts commit 5d2dfcd48f.

compiler/testData/codegen/patternMatching/is.jet

@@ -1,6 +1,6 @@
 fun typeName(a: Any?) : String {
     return when(a) {
-        is java.util.ArrayList<*> => "array list"
+        is java.util.ArrayList<Int> => "array list"
         else => "no idea"
     }
 }
@@ -8,4 +8,4 @@ fun typeName(a: Any?) : String {
 fun box() : String {
     if(typeName(java.util.ArrayList<Int> ()) != "array list") return "array list failed"
     return "OK"
-}
+}