test: comparison operator now more strict

The 'equals' comparison operator was '==' instead of the
more strict '===', so it has been changed to be more strict

PR-URL: https://github.com/nodejs/node/pull/8190
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/test-timers-zero-timeout.js

@@ -23,7 +23,7 @@ const assert = require('assert');
     assert.strictEqual(a, 'foo');
     assert.strictEqual(b, 'bar');
     assert.strictEqual(c, 'baz');
-    if (++ncalled == 3) clearTimeout(iv);
+    if (++ncalled === 3) clearTimeout(iv);
   }
 
   process.on('exit', function() {