Issue 26051. Fix for MethodDeclartion.beginToken for external.

pkg/analysis_server/test/services/correction/sort_members_test.dart

Index: pkg/analysis_server/test/services/correction/sort_members_test.dart
diff --git a/pkg/analysis_server/test/services/correction/sort_members_test.dart b/pkg/analysis_server/test/services/correction/sort_members_test.dart
index b32f5029241c047586cfdf0b04ec9f6d2490d7f5..bcc9c0c1a980a23a52afde02064f37d3b4c43f43 100644
--- a/pkg/analysis_server/test/services/correction/sort_members_test.dart
+++ b/pkg/analysis_server/test/services/correction/sort_members_test.dart
@@ -83,6 +83,22 @@ class A {
 ''');
   }
 
+  void test_classMembers_external_constructorMethod() {
+    _parseTestUnit(r'''
+class Chart {
+  external Pie();
+  external Chart();
+}
+''');
+    // validate change
+    _assertSort(r'''
+class Chart {
+  external Chart();
+  external Pie();
+}
+''');
+  }
+
   void test_classMembers_field() {
     _parseTestUnit(r'''
 class A {