[experiment] merge iterable decls in DOM #35428

Job	Run time
typecheck	46s
coverage	10m 23s
lint	57s
browser-integration	1m 28s
format	27s
knip	30s
misc	27s
self-check	59s
package-size	1m 34s
baselines	9m 48s
Test Node 24 on windows-latest	10m 32s
Test Node 14 on ubuntu-latest	11m 37s
Test Node 24 on ubuntu-latest	8m 40s
smoke	56s
Test Node lts/* on ubuntu-latest with --no-bundle	10m 48s
Test Node 14 on windows-latest	14m 45s
required	4s
	1h 24m 41s

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