IndexedDB does not update r/w index cursors that are mutated during iteration

IndexedDB does not update r/w index cursors that are mutated during iteration
https://bugs.webkit.org/show_bug.cgi?id=59822

Added tests to verify that index cursors see updates made to an object store while
iterating, assuming the cursor and updates occur within the same transaction.

Reviewed by Tony Chang.

* storage/indexeddb/mozilla/cursor-mutation-expected.txt: Added.
* storage/indexeddb/mozilla/cursor-mutation.html: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@106165 268f45cc-cd09-0410-ab3c-d52691b4dbfc