avm2: Cover special cases in Number.toExponential #30777

Job	Run time
Paths filter	8s
Build for browser tests	2m 16s
Test Node.js 22 / ubuntu-24.04	3m 19s
Test Node.js 24 / ubuntu-24.04	3m 5s
Test Node.js 22 / windows-2025	5m 0s
Test Node.js 24 / windows-2025	5m 59s
Test Node.js ${{ matrix.node_version }} / ${{ matrix.os }}	0s
Test in ${{ matrix.browser }}	0s
Test in edge	2m 18s
Test in firefox	3m 9s
Test in chrome	1m 58s
	27m 12s

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