`SseAutoReconnectStream::poll_next` recursed into itself for every event it
skips — control frames, data-less frames, and frames whose data fails to
deserialize — plus once more on every state transition.
The inner stream returns `Poll::Ready` for each event it can parse out of
already-buffered bytes, so a burst of skipped events has no yield point
between them. Each one adds a stack frame, and `poll_next` is a large frame.
A client connected to a server that emits a run of non-JSON `message` frames
overflows the stack and aborts the process.
Wrap the body in a `loop` and replace the four `self.poll_next(cx)` tail calls
with `continue`. `this` is re-derived from `self.as_mut().project()` at the top
of each iteration, so the borrows end cleanly per iteration; no other logic
changes. The diff is mostly the resulting re-indent — review with `?w=1`.
Adds `skipped_events_do_not_grow_the_stack`, which feeds 50,000 undeserializable
frames through the stream. Before this change it aborts with
`fatal runtime error: stack overflow` (SIGABRT); after, it passes.
3c8fb2a7e4