Share more code between NETWORK_SESSION and non-NETWORK_SESSION NetworkResourceLoaders

Share more code between NETWORK_SESSION and non-NETWORK_SESSION NetworkResourceLoaders
https://bugs.webkit.org/show_bug.cgi?id=150742

Reviewed by Darin Adler.

r191457 added enough code to NetworkResourceLoader to load most resources successfully if there are no errors.
It passed about 80% of LayoutTests/http and crashed sometimes.
This passes about 95% of LayoutTests/http and does not crash on any of the LayoutTests/http.
It should not change behavior of the non-NETWORK_SESSION code which is currently the default in trunk.

* NetworkProcess/NetworkResourceLoader.cpp:
(WebKit::NetworkResourceLoader::abort):
(WebKit::NetworkResourceLoader::sharedDidReceiveResponse):
(WebKit::NetworkResourceLoader::sharedDidReceiveBuffer):
(WebKit::NetworkResourceLoader::sharedDidFinishLoading):
(WebKit::NetworkResourceLoader::sharedDidFail):
(WebKit::NetworkResourceLoader::sharedWillSendRedirectedRequest):
(WebKit::NetworkResourceLoader::willPerformHTTPRedirection):
(WebKit::NetworkResourceLoader::didReceiveChallenge):
(WebKit::NetworkResourceLoader::didReceiveResponse):
(WebKit::NetworkResourceLoader::didReceiveData):
(WebKit::NetworkResourceLoader::didCompleteWithError):
(WebKit::NetworkResourceLoader::didReceiveResponseAsync):
(WebKit::NetworkResourceLoader::didReceiveBuffer):
(WebKit::NetworkResourceLoader::didFinishLoading):
(WebKit::NetworkResourceLoader::didFail):
(WebKit::NetworkResourceLoader::willSendRequestAsync):
* NetworkProcess/NetworkResourceLoader.h:
* NetworkProcess/NetworkSession.h:
(WebKit::NetworkSessionTaskClient::~NetworkSessionTaskClient):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@191848 268f45cc-cd09-0410-ab3c-d52691b4dbfc