Replace Array.isArray in test for old IE

Author: dchest

test/unittests.js

@@ -416,7 +416,7 @@ describe('encoding test', function() {
 
   it('should return Array for undefined', function(done) {
     scrypt(v.password, v.salt, { logN: v.logN, r: v.r, dkLen: v.dkLen }, function(out) {
-      assert.ok(Array.isArray(out));
+      assert.ok(Object.prototype.toString.call(out) === "[object Array]");
       done();
     });
   });