Revert of Enable QUIC 17. (https://codereview.chromium.org/276573003/)

Reason for revert:
May be bad.

Original issue's description:
> Enable QUIC 17.
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=270592

TBR=rtenneti@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/291643003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271092 0039d316-1c4b-4281-b951-d872f2087c98

net/http/http_network_session.cc

@@ -91,7 +91,7 @@ HttpNetworkSession::Params::Params()
       quic_max_packet_length(kDefaultMaxPacketSize),
       enable_user_alternate_protocol_ports(false),
       quic_crypto_client_stream_factory(NULL) {
-  quic_supported_versions.push_back(QUIC_VERSION_17);
+  quic_supported_versions.push_back(QUIC_VERSION_16);
 }
 
 HttpNetworkSession::Params::~Params() {}