MODULES: lib1, lib2, main

STEP 0:
    libs: lib1, lib2, main
    dirty js modules: lib1, lib2, main
    dirty js files:   lib1/l1, lib2/l2b, lib2/l2a, main/m, main/m.export, main
STEP 1..4:
    libs: lib1, lib2, main
    dirty js modules: lib2
    dirty js files:   lib2/l2a
STEP 5:
    libs: lib1, lib2, main
    dirty js modules: lib2
    dirty js files:   lib2/l2b
STEP 6..8:
    libs: lib1, lib2, main
    dirty js modules: lib2
    dirty js files:   lib2/l2a
STEP 9:
    libs: lib1, lib2, main
    dirty js modules: lib1, lib2
    dirty js files:   lib1/l1, lib2/l2a
STEP 10:
    libs: lib1, lib2, main
    dirty js modules: lib2
    dirty js files:   lib2/l2a
STEP 11..12:
    libs: lib1, lib2, main
    dirty js modules: lib1, lib2
    dirty js files:   lib1/l1, lib2/l2a
STEP 13..15:
    libs: lib1, lib2, main
    dirty js modules: lib2
    dirty js files:   lib2/l2a
