Backed out 2 changesets (bug 918176) for assertions
CLOSED TREE

Backed out changeset 9d5728797e77
Backed out changeset 1a895d95c88b (bug 918176)
Bug 907365 - Pseudo-derecursify the build (opt-in). r=gps

Also remove the compile tier added in bug 912856 when pseudo-derecursify is disabled.
Bug 907365 - Parallelize compile and tools tiers. r=gps
Bug 915648 - Parallelize make export. r=gps
Fixup for bug 915648 (sync config/recurse.mk with js/src/config)