Missing AST transformation with array assignment in value-place

``` haxe
using StringTools;

class Main {
static function test(inp:String){
var p = inp.split("."),
v = p[0].length - ( p[0] = p[0].substr(0,1)).length;
trace(v);
}

static function main() test("-----.------");
}
```

Dump:

```
= function(inp:String) = {
var p = inp.split(".");
var _hx_tmp = p[0].length;
var v = _hx_tmp - (p[0] = p[0].substr(0,1)).length;
haxe.Log.trace(v,{fileName : "Main.hx",lineNumber : 7,className : "Main",methodName : "test"});
}
```

C++:

``` c++
Int v = (_hx_tmp - p[(int)0] = p->__get((int)0).substr((int)0,(int)1).length);
```

Error:

```
./src/Main.cpp(34) : error C2106: '=' : left operand must be l-value
```

I'll see what I can do.