[webkit-dev] Can protocol handler be moved to the modules ?

[Gyuyoung Kim]

I file a bug to extract a client interface for register protocol handler from ChromeClient.
 
- Bug 90940 - Add ProtocolHandlerClient.h to the Modules/protocolhandler
  (https://bugs.webkit.org/show_bug.cgi?id=90940)

In order to support this, the client needs to be supplementable first. I'm working in progress.

Gyuyoung