Reason for revert:
Reverting because description was inaccurate. Will reland after updating description.
Original issue's description:
> Modify PeerConnection for end-to-end QuicDataChannel usage
>
> To allow end-to-end QuicDataChannel usage with a
> PeerConnection, RTCConfiguration has been modified to
> include a boolean for whether to do QUIC, since negotiation of
> QUIC is not implemented. If one peer does QUIC, then it will be
> assumed that the other peer must do QUIC or the connection
> will fail.
>
> PeerConnection has been modified to create data channels of type
> QuicDataChannel when the peer wants to do QUIC.
>
> WebRtcSession has been modified to use a QuicTransportChannel
> instead of a DtlsTransportChannelWrapper/DataChannel
> when QUIC should be used.
>
> Modification of previous in-flight CL: https://codereview.chromium.org/1844803002/
>
> Committed: https://crrev.com/36c8d69ce188102ae6fd48c371cf1518f08698fb
> Cr-Commit-Position: refs/heads/master@{#13470}
TBR=pthatcher@webrtc.org,zhihuang@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
Review-Url: https://codereview.webrtc.org/2146133002
Cr-Commit-Position: refs/heads/master@{#13471}
a2cd636b3d