No error in the analyzer if augment class goes before original class

[sgrekhov]

According to the specification

It is a compile-time error if:
...

• An augmenting declaration appears in a library before the library where the original declaration occurs, according to merge order.

See https://github.com/dart-lang/co19/blob/master/LanguageFeatures/Augmentation-libraries/merge_order_A01_t02.dart
There is no this error in the analyzer

// merge_order_A01_t02.dart
import augment 'merge_order_A01_t02_lib1.dart';

augment class A {} // No expected error
//            ^
// [analyzer] unspecified
// [cfe] unspecified

// merge_order_A01_t02_lib1.dart
library augment 'merge_order_A01_t02.dart'; // The new syntax is augment library, I know

class A {
}

[keertip]

/cc @scheglov

[davidmorgan]

I guess this can be closed? @scheglov thanks.