Crash in WebProcess at com.apple.WebCore: WebCore::ResourceLoader::start
This is due to a null deref in WebResourceLoadScheduler::startResourceLoad.
This is probably because the RemoveLoadIdentifier messages from Web -> NetworkProcess is asynchronous.
The WebProcess is tearing down the page (or parts of it) and therefore cleaning up the ResourceLoaders. It dispatches the message to the NetworkProcess then immediately removes the loader from it's local pending set. Before the NetworkProcess can handle that message, it is in the middle of starting resource loads so it dispatches back to the WebProcess to start the load... but it's already remvoed the record of that Loader.
For now, we should make the ASSERT(resourceLoader) be a null check with early return to mitigate this crash.
Created attachment 171527 [details]
Was also in radar as <rdar://problem/12596761>
Fixed in http://trac.webkit.org/changeset/132950