Inconsistent output compared with other JS engines

Hello,
The following code behaves strangely (inconsistent with other engines).
```
function test() {
x = 4;
do {
var ss = 100;
function ss() {
print("in func");
}
x--;
ss = 101; }
while(x>0)
}

test();
print("BT_FLAG")
```
In ChakraCore, the output is
`BT_FLAG`
However, in V8 and SpiderMonkey, output is
`SyntaxError: redeclaration of var ss:`

BT group
2018.7.24