This fixes transitioning into the ended state if we see
endOfStream from the chunk source whilst in the pending
reset state. Prior to this fix we'd still be pending a
reset, and so readData would never allow EOS to be read
by the consuming renderer.
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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=157101755
c4f7a2d62d