test: remove timers from streams test

test-stream2-readable-empty-buffer-no-eof fails on resource-constrained
machines due to its use of timers. Removing timers makes it more
reliable and doesn’t affect the validity of the test, as it only uses
relative timing relations.

Failures were noticed on freebsd10-64 in CI. I am able to replicate the
failure with `tools/test.py --repeat=100 -j 100`. When run alone, it
passes reliably.

Refs: https://github.com/nodejs/node/pull/9359
PR-URL: hkttps://github.com/nodejs/node/pull/9360
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ilkka Myller <ilkka.myller@nodefield.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-stream2-readable-empty-buffer-no-eof.js

@@ -1,5 +1,5 @@
 'use strict';
-const common = require('../common');
+require('../common');
 const assert = require('assert');
 
 const Readable = require('stream').Readable;
@@ -16,36 +16,35 @@ function test1() {
   //
   // note that this is very unusual.  it only works for crypto streams
   // because the other side of the stream will call read(0) to cycle
-  // data through openssl.  that's why we set the timeouts to call
+  // data through openssl.  that's why setImmediate() is used to call
   // r.read(0) again later, otherwise there is no more work being done
   // and the process just exits.
 
   const buf = Buffer.alloc(5, 'x');
   let reads = 5;
-  const timeout = common.platformTimeout(50);
   r._read = function(n) {
     switch (reads--) {
-      case 0:
-        return r.push(null); // EOF
-      case 1:
+      case 5:
+        return setImmediate(function() {
           return r.push(buf);
-      case 2:
-        setTimeout(r.read.bind(r, 0), timeout);
-        return r.push(Buffer.alloc(0)); // Not-EOF!
+        });
+      case 4:
+        setImmediate(function() {
+          return r.push(Buffer.alloc(0));
+        });
+        return setImmediate(r.read.bind(r, 0));
       case 3:
-        setTimeout(r.read.bind(r, 0), timeout);
+        setImmediate(r.read.bind(r, 0));
         return process.nextTick(function() {
           return r.push(Buffer.alloc(0));
         });
-      case 4:
-        setTimeout(r.read.bind(r, 0), timeout);
-        return setTimeout(function() {
-          return r.push(Buffer.alloc(0));
-        });
-      case 5:
-        return setTimeout(function() {
+      case 2:
+        setImmediate(r.read.bind(r, 0));
+        return r.push(Buffer.alloc(0)); // Not-EOF!
+      case 1:
         return r.push(buf);
-        });
+      case 0:
+        return r.push(null); // EOF
       default:
         throw new Error('unreachable');
     }