test: refactor test-child-process-stdin

Use assert.strictEqual instead of assert.equal and assert.ok

PR-URL: https://github.com/nodejs/node/pull/10420
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-child-process-stdin.js

@@ -9,8 +9,8 @@ cat.stdin.write('hello');
 cat.stdin.write(' ');
 cat.stdin.write('world');
 
-assert.ok(cat.stdin.writable);
+assert.strictEqual(true, cat.stdin.writable);
-assert.ok(!cat.stdin.readable);
+assert.strictEqual(false, cat.stdin.readable);
 
 cat.stdin.end();
 
@@ -51,8 +51,8 @@ process.on('exit', function() {
   assert.equal(0, exitStatus);
   assert(closed);
   if (common.isWindows) {
-    assert.equal('hello world\r\n', response);
+    assert.strictEqual('hello world\r\n', response);
   } else {
-    assert.equal('hello world', response);
+    assert.strictEqual('hello world', response);
   }
 });