Optimize bundle size a bit

[omgovich]

Simplify the source code to make the bundled one (ES5) lighter.

[github-actions[bot]]

Size Change: -69 B (-1%)

Total Size: 4.85 kB

Filename	Size	Change
./dist/index.js	1.75 kB	-24 B (-1%)
./dist/plugins/a11y.js	456 B	-7 B (-2%)
./dist/plugins/hwb.js	612 B	-5 B (-1%)
./dist/plugins/xyz.js	668 B	-33 B (-5%)	✅

ℹ️ View Unchanged

| Filename | Size | Change | | :--- | :---: | :---: | | `./dist/plugins/names.js` | 1.36 kB | 0 B |

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