Dollar sign problem with anonymous objects in php 7

[ciscoheat]

Running this on 4.0.0-preview4:

class Test {
    static function main() {
        var data = {"$id": 123};
        trace(Reflect.field(data, "$id"));
    }
}

Compile with haxe --php bin -main Test, and then when executing:

PHP Fatal error:  Uncaught ErrorException: Undefined variable: id in E:\Temp\bin\lib\Test.php:16
Stack trace:
#0 E:\Temp\bin\lib\Test.php(16): php\Boot::php\{closure}(8, 'Undefined varia...', 'E:\\Temp\\bin\\lib...', 16, Array)
#1 E:\Temp\bin\index.php(14): Test::main()
#2 {main}
  thrown in E:\Temp\bin\lib\Test.php on line 16