Start using the message flag in MessageEncoder/MessageDecoder
https://bugs.webkit.org/show_bug.cgi?id=108227

Reviewed by Beth Dakin.

Stop using the flags in MessageID and store the flags directly in the message instead.
This is another step towards eliminating MessageID.

* Platform/CoreIPC/Connection.cpp:
(CoreIPC::Connection::SyncMessageState::processIncomingMessage):
(CoreIPC::Connection::createSyncMessageEncoder):
(CoreIPC::Connection::sendMessage):
(CoreIPC::Connection::sendSyncMessage):
(CoreIPC::Connection::sendSyncMessageFromSecondaryThread):
(CoreIPC::Connection::dispatchSyncMessage):
(CoreIPC::Connection::dispatchMessage):
* Platform/CoreIPC/Connection.h:
* Platform/CoreIPC/MessageDecoder.cpp:
(CoreIPC::MessageDecoder::MessageDecoder):
(CoreIPC::MessageDecoder::isSyncMessage):
(CoreIPC):
(CoreIPC::MessageDecoder::shouldDispatchMessageWhenWaitingForSyncReply):
* Platform/CoreIPC/MessageDecoder.h:
(MessageDecoder):
* Platform/CoreIPC/MessageEncoder.cpp:
(CoreIPC):
(CoreIPC::MessageEncoder::MessageEncoder):
(CoreIPC::MessageEncoder::~MessageEncoder):
(CoreIPC::MessageEncoder::setIsSyncMessage):
(CoreIPC::MessageEncoder::setShouldDispatchMessageWhenWaitingForSyncReply):
* Platform/CoreIPC/MessageEncoder.h:
(MessageEncoder):
* Platform/CoreIPC/MessageFlags.h: Copied from Source/WebKit2/Platform/CoreIPC/MessageEncoder.h.
(CoreIPC):
* Platform/CoreIPC/MessageID.h:
* WebKit2.xcodeproj/project.pbxproj:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141165 268f45cc-cd09-0410-ab3c-d52691b4dbfc