[TIMOB-18310] iOS: Debugger crashed when variable is changed to another variable

When variable is changed to another variable, Debugger crashes.

It's a regression since it works in 3.4.1 GA

Steps to reproduce

1. Create a classic project 2. Copy following code in app.js file

var y = {foo:'bar'};

var win = Titanium.UI.createWindow({  
    title:'Tab 1',
    backgroundColor:'#fff'
});

var b = Ti.UI.createButton({
	title:"Shadowing",
	width:140,
	height:40,
	top:260
});
b.addEventListener('click',function() {
	var x = "foo";
	Ti.API.info("Shadow x: "+x);
});
win.add(b);
win.open();

3. Place a breakpoint in line 15 ( @ var x = "foo"; statement) 4. Debug in iOS device 5. Press the "Shadowing" button to trigger the breakpoint 6. In the Variables pane, change value of x to y (not string; variable) by double-clicking in the Value column {noformat} x should display [object Object]. It works! {noformat} 7. Repeat the Step 6 again.

Actual Result.

{noformat} Debugger crashed. Please see the attachment for more info. {noformat}

Expected Result

{noformat} Debugger should not crash {noformat}