fix sort_directives violations

See: https://dart-review.googlesource.com/c/sdk/+/196026

TEST=Code cleanup exclusively (sorting imports); no new tests.

Change-Id: I0d419bbeb73f0763175dd29eadfd84e3d0290af5
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/196223
Commit-Queue: Phil Quitslund <pquitslund@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>

Author: pq

pkg/dev_compiler/test/modular_suite_nnbd.dart

@@ -11,8 +11,8 @@ import 'dart:io';
 
 import 'package:modular_test/src/io_pipeline.dart';
 import 'package:modular_test/src/pipeline.dart';
-import 'package:modular_test/src/suite.dart';
 import 'package:modular_test/src/runner.dart';
+import 'package:modular_test/src/suite.dart';
 import 'package:package_config/package_config.dart';
 
 String packageConfigJsonPath = '.dart_tool/package_config.json';

pkg/test_runner/lib/src/options.dart

@@ -5,12 +5,12 @@
 import 'dart:convert';
 import 'dart:io';
 
-import 'package:test_runner/src/test_configurations.dart';
 import 'package:path/path.dart' as path;
 
 import 'configuration.dart';
 import 'path.dart';
 import 'repository.dart';
+import 'test_configurations.dart';
 import 'utils.dart';
 
 const _defaultTestSelectors = [

pkg/test_runner/test/test_runner_test.dart

@@ -10,15 +10,14 @@ import "dart:async";
 import "dart:io";
 
 import "package:status_file/expectation.dart";
-
 import "package:test_runner/src/command.dart";
 import "package:test_runner/src/configuration.dart";
 import "package:test_runner/src/options.dart";
 import "package:test_runner/src/process_queue.dart";
 import "package:test_runner/src/repository.dart";
 import "package:test_runner/src/test_case.dart";
-import "package:test_runner/src/test_suite.dart";
 import "package:test_runner/src/test_progress.dart" as progress;
+import "package:test_runner/src/test_suite.dart";
 
 final DEFAULT_TIMEOUT = 20;
 final LONG_TIMEOUT = 30;