[AC-1242] Webview zoomcontrol leaks window

   // this sets the background color of the master UIView (when there are no windows/tab groups on it)
   Titanium.UI.setBackgroundColor('#000');
   
   //
   // create base UI tab and root window
   //
   var win1 = Titanium.UI.createWindow({  
       title:'Win 1',
       backgroundColor:'#fff'
   });
   
   var win2 = Titanium.UI.createWindow({  
       title:'Win 2',
       backgroundColor:'#fff'
   });
   var btn = Titanium.UI.createButton({
   	title: 'Open web'
   });
   
   btn.addEventListener('click',
   	function()
   	{
   		win2.open();		
   	});
   	
   win1.add(btn);
   
   var webview = Titanium.UI.createWebView({
   	url: 'http://spininhetweb.nl',
   	height: '50%',
   	enableZoomControls: true
   });
   
   win2.addEventListener('close',function()
   {
   	win2.remove(webview);
   	win2 = null;
   });
   
   win2.add(webview);
   
   win1.open();