[Migrate] library_element.dart (extensions)

Change-Id: Ib23fa7c3f5d279f27514dc6f37ba89bce4aaf7e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403160
Reviewed-by: Konstantin Shcheglov <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>

Author: bwilkerson

pkg/analyzer/analyzer_use_new_elements.txt

@@ -142,7 +142,6 @@ 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/element.dart
-lib/src/utilities/extensions/library_element.dart
 test/error/error_reporter_test.dart
 test/generated/elements_types_mixin.dart
 test/generated/non_error_resolver_test.dart
@@ -189,6 +188,5 @@ test/src/summary/macro_test.dart
 test/src/summary/resolved_ast_printer.dart
 test/src/task/strong/dart2_inference_test.dart
 test/src/task/strong/inferred_type_test.dart
-test/src/utilities/extensions/library_element_test.dart
 test/util/element_printer.dart
 test/util/id_testing_helper.dart

pkg/analyzer/lib/src/utilities/extensions/library_element.dart

@@ -7,7 +7,6 @@ import 'package:test_reflective_loader/test_reflective_loader.dart';
 import 'ast_test.dart' as ast;
 import 'async_test.dart' as async;
 import 'collection_test.dart' as collection;
-import 'library_element_test.dart' as library_element;
 import 'object_test.dart' as object;
 import 'stream_test.dart' as stream;
 import 'string_test.dart' as string;
@@ -17,7 +16,6 @@ main() {
     ast.main();
     async.main();
     collection.main();
-    library_element.main();
     object.main();
     stream.main();
     string.main();