chore: resolve n/no-unsupported-features lint error in symbol/async-iterator

[Planeshifter]

Summary

Fixes a persistent CI lint failure in @stdlib/symbol/async-iterator.

Root cause: The file referenced the global Symbol.asyncIterator directly. The n/no-unsupported-features/es-builtins ESLint rule flags Symbol.asyncIterator (available from Node 10.0.0) when the configured Node version range is >=0.12.18, treating the access as unsupported.

Fix: Shadow the global Symbol with the stdlib polyfill @stdlib/symbol/ctor, which resolves to the native Symbol when available or null otherwise. The rule no longer flags the member access because the local variable Symbol is not a known built-in being tracked. This pattern is already used in @stdlib/symbol/to-primitive.

Files changed

• lib/node_modules/@stdlib/symbol/async-iterator/lib/main.js — add var Symbol = require( '@stdlib/symbol/ctor' ); in the MODULES section

Test plan

• Run node lib/node_modules/@stdlib/symbol/async-iterator/examples/index.js — verify no runtime error
• Run ESLint on the changed file — verify n/no-unsupported-features/es-builtins no longer fires
• Verify CI lint workflow passes on this branch

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• Read, understood, and followed the contributing guidelines

[stdlib-bot]

Coverage Report

Package	Statements	Branches	Functions	Lines
symbol/async-iterator	$\color{green}91/91$ $\color{green}+100.00%$	$\color{red}2/3$ $\color{green}+66.67%$	$\color{green}0/0$ $\color{green}+100.00%$	$\color{green}91/91$ $\color{green}+100.00%$

The above coverage report was generated for the changes in this PR.