8340899: Remove wildcard bound in PositionWindows.positionTestWindows

Backport-of: e2626db2f00d0cc9f3ff8ea374a1ccc89373e398

test/jdk/java/awt/regtesthelpers/PassFailJFrame.java

@@ -587,7 +587,7 @@ public final class PassFailJFrame {
          * @param testWindows the list of test windows
          * @param instructionUI information about the instruction frame
          */
-        void positionTestWindows(List<? extends Window> testWindows,
+        void positionTestWindows(List<Window> testWindows,
                                  InstructionUI instructionUI);
     }