REGRESSION (NetworkProcess): Trying to use appcache fallback crashes in ApplicationCacheHost::scheduleLoadFallbackResourceFromApplicationCache
https://bugs.webkit.org/show_bug.cgi?id=133007
<rdar://problem/13702706>

appcache tests often fail on the Mac WebKit2 bot
https://bugs.webkit.org/show_bug.cgi?id=82061

Reviewed by Maciej Stachowiak.

Source/WebCore:
Covered by existing tests, which this patch enables.

* WebCore.exp.in: Export ResourceLoader::cancel(const ResourceError&). It used
to be virtual, but marking subclasses final has resulted in the compiler calling
it directly from WebKitLegacy framework. Seeing that no subclass overrides it,
I then made it non-virtual.
Also export ApplicationCacheHost functions that are now used from WebKit2.

* loader/ResourceLoader.h: Made the class abstract (as I didn't realize at first
that it's always either a SubresourceLoader or a NetscapePlugInStreamLoader).
Made ResourceHandleClient functions private, as they should never be called other
than via a ResourceHandleClient pointer.

* loader/NetscapePlugInStreamLoader.h:
* loader/SubresourceLoader.h:
Marked these final.

* loader/ResourceLoader.cpp: (WebCore::ResourceLoader::willSwitchToSubstituteResource):
Added a function to be called when switching to a substitute resource. We still
need a ResourceLoader at this point, as substitute resource will be delivered through
it, but we don't want it to continue its current load.

* loader/appcache/ApplicationCacheHost.cpp:
(WebCore::ApplicationCacheHost::scheduleLoadFallbackResourceFromApplicationCache):
Call the ResourceLoader function instead of using handle, which is null when
using out of process networking.

Source/WebKit2:
* WebProcess/Network/WebResourceLoader.cpp:
(WebKit::WebResourceLoader::willSendRequest):
(WebKit::WebResourceLoader::didReceiveResponseWithCertificateInfo):
(WebKit::WebResourceLoader::didFailResourceLoad):
Perform the same appcache checks that ResourceHandleClient implementation in ResourceLoader
does. We should eventually come up with a way to share the code. Perhaps add a class that
isolates ResourceLoader from networking details? But ResourceLoader was itself supposed
to be the class that isolates DocumentLoader from networking details. So, unsure.

LayoutTests:
* platform/mac-wk2/TestExpectations: Let's enable all the appcache tests (except
for a couple that fail), and see what happens on bots. I don't see any reason
why WebKit2 would be any more flaky than WebKit1 here.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@169006 268f45cc-cd09-0410-ab3c-d52691b4dbfc