Add spec for constructor-less param

spec/api-ipc-spec.js

@@ -34,6 +34,7 @@ describe('ipc module', function () {
       assert.equal(a.foo.bar, 'baz')
       assert.equal(a.foo.baz, false)
       assert.equal(a.bar, 1234)
+      assert.equal(a.baz(Object.create(null)), 'hello')
     })
 
     it('should search module from the user app', function () {

spec/fixtures/module/no-prototype.js

@@ -1,4 +1,10 @@
 const foo = Object.create(null)
 foo.bar = 'baz'
 foo.baz = false
-module.exports = {foo: foo, bar: 1234}
+module.exports = {
+  foo: foo,
+  bar: 1234,
+  baz: function () {
+    return 'hello'
+  }
+}