Begin stubbing out session storage classes
https://bugs.webkit.org/show_bug.cgi?id=110168

Reviewed by Andreas Kling.

* UIProcess/Storage/StorageManager.cpp:
(StorageManager::StorageArea):
(WebKit):
(WebKit::StorageManager::StorageArea::create):
(WebKit::StorageManager::StorageArea::StorageArea):
(WebKit::StorageManager::StorageArea::~StorageArea):
(StorageManager::SessionStorageNamespace):
(WebKit::StorageManager::SessionStorageNamespace::isEmpty):
(WebKit::StorageManager::SessionStorageNamespace::create):
(WebKit::StorageManager::SessionStorageNamespace::SessionStorageNamespace):
(WebKit::StorageManager::SessionStorageNamespace::~SessionStorageNamespace):
(WebKit::StorageManager::SessionStorageNamespace::cloneTo):
(WebKit::StorageManager::createSessionStorageNamespaceInternal):
(WebKit::StorageManager::destroySessionStorageNamespaceInternal):
(WebKit::StorageManager::cloneSessionStorageNamespaceInternal):
* UIProcess/Storage/StorageManager.h:
(StorageManager):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@143277 268f45cc-cd09-0410-ab3c-d52691b4dbfc