[Impeller] Text scale wrong rendering (Android)

### Steps to reproduce

I've recently had some graphical problems with text transforms with Impeller on Android (tested on Android 13)

Basically, if you wrap a `Text` inside a `Tranform.scale` with `scaleY: 2` (any value greater than 1), the resulting text will have jagged diagonal lines, and vertical lines will have varying weights.

This doesn't happen with Skia.

### Expected results

This is my test with Skia:

<img width="73" height="184" alt="Image" src="https://github.com/user-attachments/assets/4422b6c5-1802-43a9-b6e0-4e2032d11361" />

### Actual results

This is my test with Impeller:

<img width="73" height="184" alt="Image" src="https://github.com/user-attachments/assets/29362549-7c2a-4087-8bf4-38c54d67ea98" />

### Code sample

<details open><summary>Code sample</summary>

```dart
import 'dart:ui' as ui;

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter_file_dialog/flutter_file_dialog.dart';

void main() {
  runApp(const MainApp());
}

class MainApp extends StatefulWidget {
  const MainApp({super.key});

  @override
  State<MainApp> createState() => _MainAppState();
}

class _MainAppState extends State<MainApp> {
  final _boundaryKey = GlobalKey();

  String rendererName() =>
      ui.ImageFilter.isShaderFilterSupported ? 'impeller' : 'skia';

  Future<void> _saveImage() async {
    final RenderRepaintBoundary boundary =
        _boundaryKey.currentContext!.findRenderObject()
            as RenderRepaintBoundary;

    final image = await boundary.toImage();
    final byteData = await image.toByteData(format: ui.ImageByteFormat.png);
    final pngBytes = byteData!.buffer.asUint8List();

    final rendererName = ui.ImageFilter.isShaderFilterSupported
        ? 'impeller'
        : 'skia';
    final params = SaveFileDialogParams(
      data: pngBytes,
      fileName: "${rendererName}_output.png",
    );
    final filePath = await FlutterFileDialog.saveFile(params: params);
    if (filePath == null) {
      print("file path was null");
    } else {
      print("Saved: $filePath");
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: RepaintBoundary(
            key: _boundaryKey,
            child: Container(
              padding: const EdgeInsets.all(20),
              color: Colors.white,
              child: Column(
                mainAxisSize: .min,
                children: [
                  for (final scale in <double>[1, 1.5, 2, 2.5])
                    Padding(
                      padding: EdgeInsetsGeometry.symmetric(vertical: 8),
                      child: Transform.scale(
                        scaleY: scale,
                        child: const Text('MAN'),
                      ),
                    ),
                ],
              ),
            ),
          ),
        ),
        floatingActionButton: FloatingActionButton.extended(
          onPressed: () => _saveImage(),
          icon: Icon(Icons.screenshot_outlined),
          label: Text("Save image"),
        ),
      ),
    );
  }
}

```

</details>


### Screenshots or Video


<details open>
<summary>Screenshots / Video demonstration</summary>

<img width="584" height="736" alt="Image" src="https://github.com/user-attachments/assets/9d9906f6-008a-41fb-a917-7c3d67ca8bc3" />

As you can see, vertical lines change weight on the Impeller image. Diagonal lines become jagged at some scales.
</details>


### Logs




### Flutter Doctor output

<details open><summary>Doctor output</summary>

```console
[✓] Flutter (Channel stable, 3.38.9, on macOS 26.2 25C56 darwin-arm64, locale it-IT) [305ms]
    • Flutter version 3.38.9 on channel stable at /Users/emanuelesalamone/Code/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 67323de285 (13 days ago), 2026-01-28 13:43:12 -0800
    • Engine revision 587c18f873
    • Dart version 3.10.8
    • DevTools version 2.51.1
    • Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-native-assets, omit-legacy-version-file, enable-lldb-debugging

[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.0) [1.509ms]
    • Android SDK at /Users/emanuelesalamone/Library/Android/sdk
    • Emulator version 36.2.12.0 (build_id 14214601) (CL:N/A)
    • Platform android-36, build-tools 35.0.0
    • ANDROID_HOME = /Users/emanuelesalamone/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
      This is the JDK bundled with the latest Android Studio installation on this machine.
      To manually set the JDK path, use: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment (build 21.0.8+-14196175-b1038.72)
    • All Android licenses accepted.

[!] Xcode - develop for iOS and macOS (Xcode 26.2) [1.195ms]
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 17C52
    ! iOS 26.2 Simulator not installed; this may be necessary for iOS and macOS development.
      To download and install the platform, open Xcode, select Xcode > Settings > Components,
      and click the GET button for the required platform.

      For more information, please visit:
        https://developer.apple.com/documentation/xcode/installing-additional-simulator-runtimes
    • CocoaPods version 1.16.2

[✓] Chrome - develop for the web [7ms]
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Connected device (3 available) [6,7s]
    • N92 (mobile)    • N92    • android-arm64  • Android 13 (API 33)
    • macOS (desktop) • macos  • darwin-arm64   • macOS 26.2 25C56 darwin-arm64
    • Chrome (web)    • chrome • web-javascript • Google Chrome 144.0.7559.133

[✓] Network resources [286ms]
    • All expected network resources are available.```

</details>


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Uh oh!

[Impeller] Text scale wrong rendering (Android) #182143

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Uh oh!

[Impeller] Text scale wrong rendering (Android) #182143

Description

Steps to reproduce

Expected results

Actual results

Code sample

Screenshots or Video

Logs

Flutter Doctor output

Metadata

Metadata

Assignees

Labels

Type

Fields

Projects

Milestone

Relationships

Development

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