Replace uses of StorageTask with StorageThread::dispatch and WTF::bind
https://bugs.webkit.org/show_bug.cgi?id=115309

Reviewed by Andreas Kling.

* storage/StorageTask.cpp:
(WebCore::StorageTask::StorageTask):
(WebCore::StorageTask::performTask):
* storage/StorageTask.h:
* storage/StorageThread.cpp:
(WebCore::StorageThread::terminate):
(WebCore::StorageThread::releaseFastMallocFreeMemoryInAllThreads):
* storage/StorageThread.h:
* storage/StorageTracker.cpp:
(WebCore::StorageTracker::importOriginIdentifiers):
(WebCore::StorageTracker::deleteAllOrigins):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149242 268f45cc-cd09-0410-ab3c-d52691b4dbfc