feat: implement `adapter.emulate` #20347

Job	Run time
lint-all	3m 9s
test-kit-cross-browser (18, windows-2019, chromium, dev)	2m 59s
test-others	2m 3s
test-kit-cross-browser (18, ubuntu-latest, firefox, dev)	2m 31s
test-kit (18, ubuntu-latest, chromium)	7m 53s
test-kit-cross-browser (18, macOS-latest, webkit, dev)	4m 11s
test-kit (20, ubuntu-latest, chromium)	8m 14s
test-kit-cross-browser (18, windows-2019, chromium, build)	3m 37s
test-kit-cross-browser (18, ubuntu-latest, firefox, build)	4m 25s
test-kit-cross-browser (18, macOS-latest, webkit, build)	4m 57s
	43m 59s

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