Try to reformat (Tools->QML/JS->Reformat File) the following test file:

import QtQuick 2.0

Item {
    Component.onCompleted: {
        for (var a in []) { 
            console.log(a) 
        }
    }
 }
 

The result will be:

 import QtQuick 2.0
 
 Item {
     Component.onCompleted: {
         for (a in []) { 
             console.log(a) 
         }
     }
 }
 

var is removed so the following error will appear while executing the program with an array containing strings for example:

Error: Invalid write to global property "a"

It seems that this new behavior comes from the last commit of qmljsreformatter.cpp which removes the handling of LocalForStatement and LocalForEachStatement.