Just a quick poc:
* Inline useState when the initializer is known to not be a function. The heuristic could be improved but will handle a large number of cases already.
* Prune effects
* Prune useRef if the ref is unused, by pruning 'ref' props on primitive components. Then DCE does the rest of the work - with a small change to allow `useRef()` calls to be dropped since function calls aren't normally eligible for dropping.
* Prune event handlers, by pruning props whose names start w "on" from primitive components. Then DCE removes the functions themselves.
Per the fixture, this gets pretty far.
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