Revert "Extract Xxd class for iOS AOT snapshotting (#16986)" (#17003)

This reverts commit 4bb7496b.

packages/flutter_tools/lib/src/commands/build_aot.dart

@@ -16,7 +16,7 @@ import '../build_info.dart';
 import '../compile.dart';
 import '../dart/package_map.dart';
 import '../globals.dart';
-import '../ios/mac.dart' show xcode, xxd;
+import '../ios/mac.dart' show xcode;
 import '../resident_runner.dart';
 import '../runner/flutter_command.dart';
 import 'build.dart';
@@ -422,14 +422,12 @@ Future<String> _buildAotSnapshot(
       await fs.file(vmSnapshotData).rename(fs.path.join(outputDir.path, kVmSnapshotData));
       await fs.file(isolateSnapshotData).rename(fs.path.join(outputDir.path, kIsolateSnapshotData));
 
-      await xxd.run(
-        <String>['--include', kVmSnapshotData, fs.path.basename(kVmSnapshotDataC)],
-        workingDirectory: outputDir.path,
-      );
-      await xxd.run(
-        <String>['--include', kIsolateSnapshotData, fs.path.basename(kIsolateSnapshotDataC)],
-        workingDirectory: outputDir.path,
-      );
+      await runCheckedAsync(<String>[
+        'xxd', '--include', kVmSnapshotData, fs.path.basename(kVmSnapshotDataC)
+      ], workingDirectory: outputDir.path);
+      await runCheckedAsync(<String>[
+        'xxd', '--include', kIsolateSnapshotData, fs.path.basename(kIsolateSnapshotDataC)
+      ], workingDirectory: outputDir.path);
 
       await xcode.cc(commonBuildOptions.toList()..addAll(<String>['-c', kVmSnapshotDataC, '-o', kVmSnapshotDataO]));
       await xcode.cc(commonBuildOptions.toList()..addAll(<String>['-c', kIsolateSnapshotDataC, '-o', kIsolateSnapshotDataO]));

packages/flutter_tools/lib/src/ios/mac.dart

@@ -39,8 +39,6 @@ IMobileDevice get iMobileDevice => context[IMobileDevice];
 
 Xcode get xcode => context[Xcode];
 
-Xxd get xxd => context[Xxd];
-
 class PythonModule {
   const PythonModule(this.name);
 
@@ -105,12 +103,6 @@ class IMobileDevice {
   }
 }
 
-class Xxd {
-  Future<RunResult> run(List<String> args, {String workingDirectory}) {
-    return runCheckedAsync(<String>['xxd']..addAll(args), workingDirectory: workingDirectory);
-  }
-}
-
 class Xcode {
   bool get isInstalledAndMeetsVersionCheck => isInstalled && isVersionSatisfactory;