Remove dead ensureDirectoryExists (#76829)

packages/flutter_tools/lib/src/base/file_system.dart

@@ -8,7 +8,6 @@ import 'package:file/file.dart';
 import 'package:file/local.dart' as local_fs;
 import 'package:meta/meta.dart';
 
-import 'common.dart' show throwToolExit;
 import 'io.dart';
 import 'platform.dart';
 import 'process.dart';
@@ -41,19 +40,6 @@ class FileSystemUtils {
 
   final Platform _platform;
 
-  /// Create the ancestor directories of a file path if they do not already exist.
-  void ensureDirectoryExists(String filePath) {
-    final String dirPath = _fileSystem.path.dirname(filePath);
-    if (_fileSystem.isDirectorySync(dirPath)) {
-      return;
-    }
-    try {
-      _fileSystem.directory(dirPath).createSync(recursive: true);
-    } on FileSystemException catch (e) {
-      throwToolExit('Failed to create directory "$dirPath": ${e.osError.message}');
-    }
-  }
-
   /// Appends a number to a filename in order to make it unique under a
   /// directory.
   File getUniqueFile(Directory dir, String baseName, String ext) {

packages/flutter_tools/test/general.shard/base/file_system_test.dart

@@ -30,16 +30,6 @@ void main() {
       );
     });
 
-    testWithoutContext('ensureDirectoryExists recursively creates a directory if it does not exist', () async {
-      fsUtils.ensureDirectoryExists('foo/bar/baz.flx');
-      expect(fs.isDirectorySync('foo/bar'), true);
-    });
-
-    testWithoutContext('ensureDirectoryExists throws tool exit on failure to create', () async {
-      fs.file('foo').createSync();
-      expect(() => fsUtils.ensureDirectoryExists('foo/bar.flx'), throwsToolExit());
-    });
-
     testWithoutContext('getUniqueFile creates a unique file name', () async {
       final File fileA = fsUtils.getUniqueFile(fs.currentDirectory, 'foo', 'json')
         ..createSync();