Remove |force_quic_port_| dead field in HttpStreamFactoryImpl::Job

|force_quic_port_| is a dead field.

BUG=475060

Review-Url: https://codereview.chromium.org/2802123002
Cr-Commit-Position: refs/heads/master@{#462693}

net/http/http_stream_factory_impl_job.h

@@ -449,9 +449,6 @@ class HttpStreamFactoryImpl::Job {
   // True if this job used an existing QUIC session.
   bool using_existing_quic_session_;
 
-  // Force quic for a specific port.
-  int force_quic_port_;
-
   scoped_refptr<HttpAuthController>
       auth_controllers_[HttpAuth::AUTH_NUM_TARGETS];