Regression(r143273): Caused a lot of tests to time out
https://bugs.webkit.org/show_bug.cgi?id=110212

Reviewed by Anders Carlsson.

StorageManager::destroySessionStorageNamespace() and StorageManager::cloneSessionStorageNamespace()
should call their respective "*Internal" equivalent instead of calling themselves. This lead to
a lot of time outs on our build bots.

* UIProcess/Storage/StorageManager.cpp:
(WebKit::StorageManager::destroySessionStorageNamespace):
(WebKit::StorageManager::cloneSessionStorageNamespace):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143332 268f45cc-cd09-0410-ab3c-d52691b4dbfc