Bug 1401592: Test cases. r=jib

...edia/webrtc/tests/mochitests/mochitest_peerconnection.ini

dom/media/webrtc/tests/mochitests/simulcast.js

.../mochitests/test_peerConnection_encodingsNegotiation.html

...tests/mochitests/test_peerConnection_scaleResolution.html

...c/tests/mochitests/test_peerConnection_setParameters.html

...tests/test_peerConnection_setParameters_maxFramerate.html

...t_peerConnection_setParameters_scaleResolutionDownBy.html

...tests/mochitests/test_peerConnection_simulcastAnswer.html

...ests/test_peerConnection_simulcastAnswer_lowResFirst.html

...ochitests/test_peerConnection_simulcastOddResolution.html

.../tests/mochitests/test_peerConnection_simulcastOffer.html

...tests/test_peerConnection_simulcastOffer_lowResFirst.html

...-hint/RTCRtpSendParameters-degradationPreference.html.ini

.../webrtc-extensions/RTCRtpParameters-maxFramerate.html.ini

.../meta/webrtc-priority/RTCRtpParameters-encodings.html.ini

...ta/webrtc/RTCPeerConnection-addTransceiver.https.html.ini

...meta/webrtc/RTCPeerConnection-transceivers.https.html.ini

...-platform/meta/webrtc/RTCRtpParameters-encodings.html.ini

...tform/meta/webrtc/RTCRtpParameters-transactionId.html.ini

...g/web-platform/meta/webrtc/idlharness.https.window.js.ini