Add stubbed out WebBackForwardListProxy

Reviewed by Anders Carlsson.

- No behavior change.
- Rename the old WebBackForwardListProxy to WebBackForwardList since it
  will be the implementation, not the proxy.

* UIProcess/API/C/WKAPICast.h:
* UIProcess/API/C/WKBackForwardList.cpp:
* UIProcess/API/C/WKPage.cpp:
* UIProcess/WebBackForwardList.cpp: Copied from UIProcess/WebBackForwardListProxy.cpp.
* UIProcess/WebBackForwardList.h: Copied from UIProcess/WebBackForwardListProxy.h.
(WebKit::WebBackForwardList::create):
* UIProcess/WebBackForwardListProxy.cpp: Removed.
* UIProcess/WebBackForwardListProxy.h: Removed.
* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::WebPageProxy):
* UIProcess/WebPageProxy.h:
(WebKit::WebPageProxy::backForwardList):
* WebKit2.xcodeproj/project.pbxproj:
* WebProcess/WebPage/WebBackForwardListProxy.cpp: Added.
* WebProcess/WebPage/WebBackForwardListProxy.h: Added.
(WebKit::WebBackForwardListProxy::create):
* win/WebKit2.vcproj:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@62805 268f45cc-cd09-0410-ab3c-d52691b4dbfc