[element model] migrate `library_annotations`

Bug: https://github.com/dart-lang/linter/issues/5099
Change-Id: I386be7cbd2768d031ab42cc47d5b007e1f6d8478
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/389360
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>

pkg/analyzer/lib/dart/element/element.dart

diff --git a/pkg/analyzer/lib/dart/element/element.dart b/pkg/analyzer/lib/dart/element/element.dart
index 64b5f71..2740678 100644
--- a/pkg/analyzer/lib/dart/element/element.dart
+++ b/pkg/analyzer/lib/dart/element/element.dart
@@ -897,6 +897,16 @@
   /// other element.
   Element? get element;
 
+  /// Returns the element referenced by this annotation.
+  ///
+  /// In valid code this element can be a [GetterElement] of a constant
+  /// top-level variable, or a constant static field of a class; or a
+  /// constant [ConstructorElement].
+  ///
+  /// In invalid code this element can be `null`, or a reference to any
+  /// other element.
+  Element2? get element2;
+
   /// Whether the annotation marks the associated function as always throwing.
   bool get isAlwaysThrows;
 

pkg/analyzer/lib/src/dart/element/element.dart

diff --git a/pkg/analyzer/lib/src/dart/element/element.dart b/pkg/analyzer/lib/src/dart/element/element.dart
index 299017e..43ac505 100644
--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@@ -2079,6 +2079,11 @@
   AnalysisContext get context => compilationUnit.library.context;
 
   @override
+  Element2? get element2 {
+    return element?.asElement2;
+  }
+
+  @override
   bool get isAlwaysThrows => _isPackageMetaGetter(_alwaysThrowsVariableName);
 
   @override

pkg/linter/lib/src/rules/library_annotations.dart

diff --git a/pkg/linter/lib/src/rules/library_annotations.dart b/pkg/linter/lib/src/rules/library_annotations.dart
index d30a0c1..d1c0d2a 100644
--- a/pkg/linter/lib/src/rules/library_annotations.dart
+++ b/pkg/linter/lib/src/rules/library_annotations.dart
@@ -4,7 +4,7 @@
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
-import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/dart/element/element2.dart';
 // ignore: implementation_imports
 import 'package:analyzer/src/dart/element/extensions.dart';
 import 'package:meta/meta_meta.dart';
@@ -89,9 +89,9 @@
     required String libraryName,
     required String className,
   }) {
-    var element = this.element;
-    return element is ConstructorElement &&
-        element.enclosingElement3.name == className &&
-        element.library.name == libraryName;
+    var element = element2;
+    return element is ConstructorElement2 &&
+        element.enclosingElement2.name == className &&
+        element.library2?.name == libraryName;
   }
 }