[Windows WebKit2] Use cookies set in WebKit1

[Windows WebKit2] Use cookies set in WebKit1
https://bugs.webkit.org/show_bug.cgi?id=60274

Reviewed by Darin Adler.

Source/WebCore:

Make sure any Private Browsing session is based off the default session.

* platform/network/cf/ResourceHandleCFNet.cpp:
(WebCore::ResourceHandle::createPrivateBrowsingStorageSession):

Source/WebKit2:

Properly handle the case where there is no serialized default storage session by not trying
to encode or decode 0, while still making sure to decode any valid storage session.

* Shared/WebProcessCreationParameters.cpp:
(WebKit::WebProcessCreationParameters::WebProcessCreationParameters):
(WebKit::WebProcessCreationParameters::encode):
Only encode the storage session if there is one to encode.
(WebKit::WebProcessCreationParameters::decode):
Only decode the storage session there is one to decode.
* Shared/WebProcessCreationParameters.h:

WebKitLibraries:

Update WKSI with the changes to wkCreatePrivateStorageSession.

* win/include/WebKitSystemInterface/WebKitSystemInterface.h:
* win/lib/WebKitSystemInterface.lib:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@86369 268f45cc-cd09-0410-ab3c-d52691b4dbfc