Adjust the "handles resize correctly, with idsToKeep provided" unit-test (PR 14238 follow-up)

This small change will help validate an important part of the upcoming re-factoring, regarding the *correct* iteration of the `Set` in the `PDFPageViewBuffer.resize` method in particular.

test/unit/base_viewer_spec.js

@@ -136,12 +136,12 @@ describe("BaseViewer", function () {
 
       // Ensure that decreasing the size will evict the correct views,
       // while re-ordering the remaining ones correctly.
-      buffer.resize(3, new Set([1, 2, 3]));
+      buffer.resize(3, new Set([1, 2, 5]));
 
       expect(buffer._buffer).toEqual([
         viewsMap.get(1),
         viewsMap.get(2),
-        viewsMap.get(3),
+        viewsMap.get(5),
       ]);
     });