https://bugs.webkit.org/show_bug.cgi?id=97738

Reviewed by Tony Chang.

Process multiple tasks from the pending queue(s) when the timer fires. The
task may initiate new tasks that change which queue is active (e.g. indexing
operations) so the loop must re-check each tick which queue to use.

In DumpRenderTree, time to make 20k puts/20k gets dropped from 3.2s to 2.0s (-37%);
in Chromium's content_shell, the time dropped from 8.1s to 4.6s (-42%).

No new tests - just perf improvements, covered by (nearly) all existing IDB tests.

* Modules/indexeddb/IDBTransactionBackendImpl.cpp:
(WebCore::IDBTransactionBackendImpl::abort): Use takeFirst() to clean up code.
(WebCore::IDBTransactionBackendImpl::taskTimerFired): Process as many tasks as are available.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@134529 268f45cc-cd09-0410-ab3c-d52691b4dbfc