[Migrate] ast.dart (extentions)

Change-Id: Ia824f614e450c56b98fd5f38f1dec17cb421a3f3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/402905
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>
diff --git a/pkg/analyzer/analyzer_use_new_elements.txt b/pkg/analyzer/analyzer_use_new_elements.txt
index ccf5f25..364fc91 100644
--- a/pkg/analyzer/analyzer_use_new_elements.txt
+++ b/pkg/analyzer/analyzer_use_new_elements.txt
@@ -143,7 +143,6 @@
 lib/src/test_utilities/find_element.dart
 lib/src/test_utilities/find_node.dart
 lib/src/test_utilities/mock_sdk_elements.dart
-lib/src/utilities/extensions/ast.dart
 lib/src/utilities/extensions/element.dart
 lib/src/utilities/extensions/flutter.dart
 lib/src/utilities/extensions/library_element.dart
diff --git a/pkg/analyzer/lib/src/utilities/extensions/ast.dart b/pkg/analyzer/lib/src/utilities/extensions/ast.dart
index ebb8eec..f8fd39f 100644
--- a/pkg/analyzer/lib/src/utilities/extensions/ast.dart
+++ b/pkg/analyzer/lib/src/utilities/extensions/ast.dart
@@ -4,7 +4,6 @@
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
-import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/element2.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 
@@ -27,22 +26,6 @@
     return result;
   }
 
-  /// The [ExecutableElement] of the enclosing executable [AstNode].
-  ExecutableElement? get enclosingExecutableElement {
-    for (var node in withParents) {
-      if (node is FunctionDeclaration) {
-        return node.declaredElement;
-      }
-      if (node is ConstructorDeclaration) {
-        return node.declaredElement;
-      }
-      if (node is MethodDeclaration) {
-        return node.declaredElement;
-      }
-    }
-    return null;
-  }
-
   /// The [ExecutableElement2] of the enclosing executable [AstNode].
   ExecutableElement2? get enclosingExecutableElement2 {
     for (var node in withParents) {
@@ -176,10 +159,11 @@
 extension CompilationUnitExtension on CompilationUnit {
   /// Whether this [CompilationUnit] is found in a "test" directory.
   bool get inTestDir {
-    var declaredElement = this.declaredElement;
-    if (declaredElement == null) return false;
-    var pathContext = declaredElement.session.resourceProvider.pathContext;
-    var path = declaredElement.source.fullName;
+    var declaredFragment = this.declaredFragment;
+    if (declaredFragment == null) return false;
+    var pathContext =
+        declaredFragment.element.session.resourceProvider.pathContext;
+    var path = declaredFragment.source.fullName;
     return switch (pathContext.separator) {
       '/' => const [
           '/test/',