MODULES: lib1, lib2, main

STEP 0:
    libs: lib1, lib2, main
    dirty js: lib1, lib2, main
STEP 1..2:
    libs: lib1, lib2, main
    dirty js: lib1
STEP 3..5:
    libs: lib1, lib2, main
    dirty js: lib1, lib2
STEP 6:
    libs: lib1, lib2, main
    dirty js: lib2