We disabled x-webkit-deflate-frame support on r751 accidentally. It's restored by r760.
Sorry for inconvenience.
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As the deflate-frame is deprecated and the standardization WG is working on permessage-deflate, pywebsocket will stop supporting the deflate-frame (including x-webkit-deflate-frame which Chrome supports now) at some point maybe after Chrome/Blink and WebKit switch to the permessage-deflate.
Thanks