8306785: fix deficient spliterators for Sequenced Collections

Reviewed-by: psandoz

src/java.base/share/classes/java/util/ArrayList.java

@@ -1509,7 +1509,10 @@ public class ArrayList<E> extends AbstractList<E>
         public Spliterator<E> spliterator() {
             checkForComodification();
 
-            // ArrayListSpliterator not used here due to late-binding
+            // This Spliterator needs to late-bind to the subList, not the outer
+            // ArrayList. Note that it is legal for structural changes to be made
+            // to a subList after spliterator() is called but before any spliterator
+            // operations that would causing binding are performed.
             return new Spliterator<E>() {
                 private int index = offset; // current index, modified on advance/split
                 private int fence = -1; // -1 until used; then one past last index
@@ -1628,9 +1631,7 @@ public class ArrayList<E> extends AbstractList<E>
          * be worthwhile in practice. To carry this out, we (1) lazily
          * initialize fence and expectedModCount until the latest
          * point that we need to commit to the state we are checking
-         * against; thus improving precision.  (This doesn't apply to
-         * SubLists, that create spliterators with current non-lazy
-         * values).  (2) We perform only a single
+         * against; thus improving precision. (2) We perform only a single
          * ConcurrentModificationException check at the end of forEach
          * (the most performance-sensitive method). When using forEach
          * (as opposed to iterators), we can normally only detect