node: enable `--harmony` by default

BIG & CRAZY

Signed-off-by: Refael Ackermann <refack@gmail.com>
crypto: remove duplicate declaration

Caused crashes in `Debug`
test: fixture certificate expired
test: tweaking test code

test-child-process-fork-net2.js - time limit too strict
test-cluster-worker-init.js - time limit too strict
test-force-repl.js - time limit too strict
test-fs-empty-readStream.js - time limit too strict
test-fs-realpath.js - Windows case normalization
test-fs-realpath.js - Windows case normalization
src: protect in case there is no toString()

triggered by test-regress-GH-4015.js with Debug build