http-client-impl: drop usage of ByteBufferReference temporarily. Using it properly requires changing FlowTube to work with List<BBR> or BBR[] instead of List<BB>. May be added back later if there is a performance gain.

^build/
^dist/
^.idea/
nbproject/private/
^webrev
^.src-rev$
^.jib/
\.DS_Store
\.metadata/
\.recommenders/
test/nashorn/script/external
test/nashorn/lib
NashornProfile.txt