[TIMOB-26490] iOS: WKWebView does not stop playing videos on iPad

Hello, WKWebView does not stop playing videos on iPad on latest SDK. Although its stop playing the video on iPhone. We have tested this issue on the following environment: Appcelerator Command-Line Interface, version 7.0.6 SDK: 7.4.1.GA Devices: iPhone 5s(12.0.1), and iPad Simulator Ti.WKWebView module version: 2.8.3 from [here](https://github.com/appcelerator-modules/Ti.WKWebView/releases) *Steps to reproduce the issue:* 1) add the attached app.js code into your project 2) Run it on iOS 12.0 iPad device 3) Click on "click to open videos" button 4) Play the video, once the video is started playing, click on the back button or goto the background by clicking on Home button 5) Video is playing even after closing the window *Test Code:* app.js file

var mainWin = Ti.UI.createWindow({
	backgroundColor : 'white'
});

var btn = Ti.UI.createButton({
	title : 'click to open videos',
	color : 'white',
	backgroundColor : 'black',
	width : "50%",
	height : '20%'
});
mainWin.add(btn);
btn.addEventListener('click', function() {
	var win = Ti.UI.createWindow({
		backgroundColor : 'white'
	});
	var backBtn = Ti.UI.createButton({
		title : 'Back',
		color : 'white',
		backgroundColor : 'black',
		top : 10
	});
	backBtn.addEventListener('click', function() {
		win.close();
	});
	var WK = require('ti.wkwebview');
	var webview = WK.createWebView({
		url : 'https://vimeo.com/album/5202279',
		top : 50
	});
	win.add(backBtn);
	win.add(webview);
	win.open();
});
mainWin.open(); 

Thanks