Add a mode to test implicit dynamic with private imports

test/stdlib/ArrayBridge.swift.gyb

@@ -21,6 +21,9 @@
 // REQUIRES: executable_test
 // REQUIRES: objc_interop
 
+// Requires swift-version 4
+// UNSUPPORTED: swift_test_mode_optimize_none_with_implicit_dynamic
+
 import Foundation
 import ArrayBridgeObjC
 import StdlibUnittest