Fix signals aborting context updates

[marvinhagemeister]

We noticed that a component that subscribes to a signal may block updates in a scenario where the signal didn't update, but context values did.

Authored together with @developit and @mdentremont in a paring session.

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Latest commit: 8630d1b

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[github-actions]

Size Change: +140 B (0%)

Total Size: 68.5 kB

Filename	Size	Change
docs/dist/assets/index.********.js	836 B	-243 B (-23%)	🎉
docs/dist/assets/signals.module.********.js	2.1 kB	+130 B (+7%)	🔍
docs/dist/demos-********.js	3.35 kB	-1 B (0%)
packages/preact/dist/signals.js	1.33 kB	+129 B (+11%)	⚠️
packages/preact/dist/signals.mjs	1.27 kB	+125 B (+11%)	⚠️

ℹ️ View Unchanged

Filename	Size
docs/dist/assets/client.********.js	46.4 kB
docs/dist/assets/jsxRuntime.module.********.js	282 B
docs/dist/assets/preact.module.********.js	4 kB
docs/dist/assets/signals-core.module.********.js	1.36 kB
docs/dist/assets/style.********.js	21 B
docs/dist/assets/style.********.css	1.21 kB
docs/dist/basic-********.js	244 B
docs/dist/nesting-********.js	1.13 kB
docs/dist/react-********.js	239 B
packages/core/dist/signals-core.js	1.42 kB
packages/core/dist/signals-core.mjs	1.44 kB
packages/react/dist/signals.js	1 kB
packages/react/dist/signals.mjs	919 B

_{compressed-size-action}

[marvinhagemeister]

Managed to narrow the remaining issue to a reproducible test case.

[marvinhagemeister]

Closing as the actual source of the problem was a bug in Preact. See preactjs/preact#3889 .