Different output compared with other JS engines when function name is same to variable name

Hello,
    Running following js code:
------------------------
function test() {
    x = 4;
    do {
        var ss = 100;
        function ss() {
            print("in func");
        }
        x--;
        ss = 101; 
    } while(x>0)
}

test();
print("BT_FLAG")
------------------------
Output of V8 and Firefoz:
 SyntaxError: Identifier 'ss' has already been declared

However, output of jsc:
BT_FLAG

BT group
2018.7.24