I.scrollTo() cause error when locator ignored on mobile devices

#### What are you trying to achieve?

`I.scrollTo(0, 1000)` in iphone

#### What do you get instead?

Error message:

```
Malformed type for "xoffset" parameter of command touchScroll
Expected: number
Actual: null

For more info see https://github.com/SeleniumHQ/selenium/wiki/JsonWireProtocol#sessionsessionidtouchscroll
```

### Details

* CodeceptJS version: 2.1.3
* NodeJS Version: v8.15.1
* Operating System: maxOS mojave 10.14.6
* WebDriverIO version 5.12.1

https://github.com/Codeception/CodeceptJS/blob/58680c433c0591b37db92117130ce41205919285/lib/helper/WebDriver.js#L1339 is wrong, based on document here, the code `this.browser.touchScroll(locator, offsetX, offsetY)` should be changed to `this.browser.touchScroll(offsetX, offsetY, locator)` .