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arturovt
3ac3753cd9
Three small, behavior-neutral cleanups to maybeRemoveStaleArrayFields:
1. Avoid allocating an empty Set when prevData.byTrackingKey is
undefined. new Set(undefined) previously created an unused empty
Set on every call for parents with no tracking keys.
2. Guard the per-element tracking-key check on `oldTracking` being
defined, skipping the isObject/hasOwn check entirely when there's
nothing to track.
3. Replace childValue.hasOwnProperty(identitySymbol) with
Object.hasOwn(childValue, identitySymbol). hasOwnProperty throws
on null-prototype array elements (Object.create(null)), which
would crash computeChildrenMap. Object.hasOwn is null-prototype-safe
and preserves "own property" semantics (does not match inherited
identitySymbol values).
4. Replace `data.byTrackingKey?.delete(id)` with
`data.byTrackingKey!.delete(id)`. The optional chaining was dead:
if oldTracking.size > 0, prevData.byTrackingKey (and therefore
data.byTrackingKey, same Map reference via the spread) is always
defined. The `?.` masked this invariant; `!` documents it and
would surface a runtime error instead of a silent no-op if the
invariant is ever violated.
Verified via performance.mark/measure instrumented directly inside
the function (count=1 call for a single-field edit in both cases).
Total duration dropped from ~0.7ms to ~0.1ms, consistent with the
avoided Set allocation in (1) and (2).
(cherry picked from commit 73ab88e65b)