###### Version

Version: 3.0.0 (fea10bb7)

###### Execution steps 

    /.jsvu/jerry Testcase.js

###### Test case 1

```js
var foo = function(it) {
    var a = [...it, , ];
    print(a);
    print(a.length);
};
var Parameter0 = [1, 2];
foo(Parameter0);
```

###### Output 1

```
1,2
2
```

###### Expected behavior

```
1,2,
3
```

###### Test case 2

```js
var foo = function(it) {
    var arr = [ , ];
    var a = it.concat(arr);
    print(a);
    print(a.length);
};
var Parameter0 = [1, 2];
foo(Parameter0);
```

###### Output 2

```
1,2,
3
```

###### Description

I tested on multiple JS engines, test case 1 and test case 2 have the same semantics, they should have the same output. But jerry outputs abnormal results when executing test case 1.


Array concatenation exception
This is a GitHub Issue
repo:jerryscript
owner:jerryscript-project
Title : Array concatenation exception
Issue date:

--- start body ---
###### Version

Version: 3.0.0 (fea10bb7)

###### Execution steps 

    /.jsvu/jerry Testcase.js

###### Test case 1

```js
var foo = function(it) {
    var a = [...it, , ];
    print(a);
    print(a.length);
};
var Parameter0 = [1, 2];
foo(Parameter0);
```

###### Output 1

```
1,2
2
```

###### Expected behavior

```
1,2,
3
```

###### Test case 2

```js
var foo = function(it) {
    var arr = [ , ];
    var a = it.concat(arr);
    print(a);
    print(a.length);
};
var Parameter0 = [1, 2];
foo(Parameter0);
```

###### Output 2

```
1,2,
3
```

###### Description

I tested on multiple JS engines, test case 1 and test case 2 have the same semantics, they should have the same output. But jerry outputs abnormal results when executing test case 1.


--- end body ---
