Update assert in BitSetArray::Iterator::prepareCopy Prior to a mutation of the bitset, mCurrentIterator would have been from mParent but post-mutation subsequent iterators are obtained from mParentCopy. Assert that the end() markers for both containers are the same. Bug: angleproject:3877 Change-Id: Ia29abd2acc0014522ef5856a88d8ec227cf9f19d Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2693813 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>