Avoid clonning input js code if status is notmodified #364

Job	Run time
wasm-pack (linux 64 bits)	6m 40s
static-checks (lint)	12s
test-native (linux 64 bits, ubuntu-latest)	1m 42s
static-checks (clippy)	53s
test-native (windows 64 bits, windows-latest)	4m 19s
check-versions	6s
test-native (macos 64 bits, macos-latest)	1m 22s
compile-v8-and-run-tests	3m 56s
test-docker (alpine 64 bits, test.alpine.Dockerfile)	39s
test-native-js (linux 64 bits, ubuntu-latest, x64)	22s
test-native-js (windows 64 bits, windows-latest, x64)	55s
test-native-js (windows 32 bits, windows-latest, x86)	55s
test-native-js (macos 64 bits, macos-latest, x64)	35s
all-good	1s
	22m 37s

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