https://bugs.webkit.org/show_bug.cgi?id=114962

Reviewed by Eric Carlson.

Work around a bug in AVAssetResourceLoader by using a generic, non-main dispatch queue
to recieve AVAssetResourceLoaderDelegate callbacks, and then marshalling those
callbacks to the main thread asynchronously.

* platform/graphics/avfoundation/objc/MediaPlayerPrivateAVFoundationObjC.mm:
(WebCore::globalLoaderDelegateQueue): Added.
(WebCore::MediaPlayerPrivateAVFoundationObjC::createAVAssetForURL): Use the new global queue.
(-[WebCoreAVFLoaderDelegate resourceLoader:shouldWaitForLoadingOfRequestedResource:]):
    Marshall the request to the main queue, and return YES (wait) immediately.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@148906 268f45cc-cd09-0410-ab3c-d52691b4dbfc