bootstrap_node.js: Make reading from stdin configurable

[cmfcmf]

Currently, Node.js is hacked to never read from stdin:

node/lib/internal/bootstrap_node.js

Lines 200 to 210 in 734d0d6

	if (true) {
	// TODO (cf): This should only happen if we run node via node::lib::Initialize().
	// It should not run if we call node::lib::Start().
	// Do nothing. Calling evalScript is necessary however, because it sets
	// globals.require to the require function.
	// Otherwise, require doesn't work.
	console.log('Embedded mode');
	evalScript('[eval]');
	// If -i or --interactive were passed, or stdin is a TTY.
	} else if (process._forceRepl || NativeModule.require('tty').isatty(0)) {

Add a command line parameter (?) to toggle this behaviour.

[justus-hildebrand]

Are we keeping stdin-reading for any other reason than backwards compatibility (old Start() behaviour)? Can't think of one right now.

Should we decide to not allow stdin (making us not perfectly backwards compatible, should still be considered though IMO), we could use the preprocessor flag NODE_SHARED_MODE to only include the change made in 734d0d6 when building as a shared lib

[justus-hildebrand]

current point of discussion: do we want to add a way to query whether node is running as a library or as a native app? If so, how? Environment variable? JS getter function? Another way I have not thought of? (will add decision once it was made)

[justus-hildebrand]

did not go with env-variable mentioned earlier, instead gave direct control over wether to spawn REPL or not