abstract Map key types prevent inlining

```haxe
abstract A(Int) from Int {}

class Main {
static function main() {
var m1 = new Map();
m1.set(0, 0); // inlined

var m2 = new Map();
m2.set(0, 0); // not inlined
}
}
```

```js
Main.main = function() {
var m1_h = { };
m1_h[0] = 0;
var m2 = new haxe_ds_IntMap();
m2.set(0,0);
};
```