Description:
------------
Allowing syntax like {$c->worker}() would help to solve ambiguity.

Test script:
---------------
<?php
class Worker {
  public function __invoke() {
    echo "invoked\n";
  }
}

class Caller {
  public $worker;

  public function __construct($worker) {
    $this->worker = $worker;
  }

  public function __call($name, $arguments) {
    echo "called\n";
  }
}

$c = new Caller(new Worker());
echo $c->worker(); // should output "called"
echo {$c->worker}(); // should output "invoked"
?>

Expected result:
----------------
called
invoked

Actual result:
--------------
Parse error: syntax error, unexpected '{'