https://bugs.webkit.org/show_bug.cgi?id=33698

Reviewed by Oliver Hunt.

JavaScriptCore:

* wtf/TypeTraits.cpp: Added tests for the new type traits.
* wtf/TypeTraits.h:
(WTF::IsSubclass): Determines if a class is a derived from another class.
(WTF::IsSubclassOfTemplate): Determines if a class is a derived from a
template class (with one parameter that is unknown).
(WTF::RemoveTemplate): Reveals the type for a template parameter.

WebCore:

Now the copier is able to handle types that derive from ThreadSafeShared.

No change functionality so no new tests.

* loader/WorkerThreadableLoader.cpp:
(WebCore::WorkerThreadableLoader::MainThreadBridge::cancel): Remove unnecessary cast.
(WebCore::WorkerThreadableLoader::MainThreadBridge::clearClientWrapper): Ditto.
* loader/WorkerThreadableLoader.h:
Change to use the derived class instead of the ThreadSafeShared version.
* platform/CrossThreadCopier.cpp:
Add the new template parameter throughout the classes and adjust the class that
handles ThreadSafeShared to allow for derived types.
* platform/CrossThreadCopier.h:
Add another template parameter to be able to detect classes that derive
from ThreadSafeShared.
* websockets/WorkerThreadableWebSocketChannel.cpp:
Removed unnecessary casts and changed a type to use the derived class instead of
the ThreadSafeShared version.
(WebCore::WorkerThreadableWebSocketChannel::Peer::Peer):
(WebCore::workerContextDidSend):
(WebCore::workerContextDidGetBufferedAmount):
(WebCore::workerContextDidConnect):
(WebCore::workerContextDidReceiveMessage):
(WebCore::workerContextDidClose):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::setWebSocketChannel):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::mainThreadCreateWebSocketChannel):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::send):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::bufferedAmount):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::clearClientWrapper):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::setMethodNotCompleted):
(WebCore::WorkerThreadableWebSocketChannel::Bridge::waitForMethodCompletion):
* websockets/WorkerThreadableWebSocketChannel.h:
(WebCore::WorkerThreadableWebSocketChannel::Peer::create): Changed a type to use the
derived class instead of the ThreadSafeShared version.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@53568 268f45cc-cd09-0410-ab3c-d52691b4dbfc