Linter complaints about double underline

[zoechi]

1st case:

I have a public getter

List<String> get demos => __demos;

a private setter

set _demos(List<String> demos) {
  __demos = demos;
  notifyPath('demos', demos); // Polymer requires it
}
and a private backing field `__demos`

> [lint] Name non-constant identifiers using lowerCamelCase.

**2nd case**
```dart
@reflectable
void onMouseClick(_, __) { // signature required by Polymer
   doSomething();
}

[lint] Name non-constant identifiers using lowerCamelCase.

Quite annoying
See also #57201

[pq]

Fixed w/ c5723d1.