Add mock DTMFSender support.
https://bugs.webkit.org/show_bug.cgi?id=133298

Patch by Kiran <kiran.guduru@samsung.com> on 2014-06-02
Reviewed by Eric Carlson.

Source/WebCore:
Implemented mock implementation for RTCPeerConnectionHandler. Now creating
RTCDTMFSenderHandlerMock and returning while creating DTMFSender instead of
returning null.

Test: fast/mediastream/RTCPeerConnection-dtmf.html.

* CMakeLists.txt:
* platform/mock/RTCDTMFSenderHandlerMock.cpp: Added.
(WebCore::RTCDTMFSenderHandlerMock::RTCDTMFSenderHandlerMock):
(WebCore::RTCDTMFSenderHandlerMock::setClient):
(WebCore::RTCDTMFSenderHandlerMock::insertDTMF):
* platform/mock/RTCDTMFSenderHandlerMock.h: Added.
* platform/mock/RTCPeerConnectionHandlerMock.cpp:
(WebCore::RTCPeerConnectionHandlerMock::createDTMFSender):

LayoutTests:
* fast/mediastream/RTCPeerConnection-dtmf-expected.txt:
* fast/mediastream/RTCPeerConnection-dtmf.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@169528 268f45cc-cd09-0410-ab3c-d52691b4dbfc