When using $map mode '=' the value should be available in the scope right away

[pavelgj]

Right now:

class FooComponent {
  static var $map = {
    'bar': '='
  };

  FooComponent(Scope scope) {
    expect(scope.bar, isNull);
    scope.$watch(() => scope.bar, (value) {
      if (value != null) { // watcher will fire with a null the first time.
        // use the value.
      }
    });
  }
}

The value should be available on the scope before the component is instantiated.