Remove and also ignore unnecessary imports (flutter#89796)

Author: srawlins

analysis_options.yaml

@@ -36,6 +36,9 @@ analyzer:
     # Stream and not importing dart:async
     # Please see https://github.com/flutter/flutter/pull/24528 for details.
     sdk_version_async_exported_from_core: ignore
+    # TODO(https://github.com/flutter/flutter/issues/74381):
+    # Clean up existing unnecessary imports, and remove line to ignore.
+    unnecessary_import: ignore
     # Turned off until null-safe rollout is complete.
     unnecessary_null_comparison: ignore
   exclude:

dev/integration_tests/deferred_components_test/lib/component1.dart

@@ -5,7 +5,6 @@
 library component1;
 
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 
 
 class LogoScreen extends StatelessWidget {

dev/integration_tests/deferred_components_test/lib/main.dart

@@ -5,7 +5,6 @@
 import 'dart:async';
 
 import 'package:flutter/material.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_driver/driver_extension.dart';
 
 import 'component1.dart' deferred as component1;

dev/tools/test/dartdoc_test.dart

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 import 'package:platform/platform.dart';
-import 'package:process/process.dart';
 import 'package:test/test.dart';
 
 import '../../../packages/flutter_tools/test/src/fake_process_manager.dart';