Repository: flutter
Issue: [Linux] Image gets rendered with nearest filtering 
Labels: engine,a: quality,platform-linux,a: images,a: desktop,P2,team-linux,triaged-linux

## Steps to Reproduce

<!-- You must include full steps to reproduce so that we can reproduce the problem. -->

1. Clone and https://github.com/flutter/gallery.
2.
```
flutter config --enable-linux-desktop
flutter create .
flutter run -d linux
```

**Expected results:**

Flutter logo should be rendered with reasonable anti-aliasing.

**Actual results:**

Flutter logo looks weird.

![Screenshot from 2020-09-21 17-21-42](https://user-images.githubusercontent.com/12389383/93763155-e4d2fa00-fc4b-11ea-9018-e970b9194864.png)

Inspection with RenderDoc shows that the image is rendered with `GL_TEXTURE_{MIN,MAG}_FILTER = GL_NEAREST`. Which is not the behavior on other platforms, at least.

<details>
  <summary>Logs</summary>

<!--
      Run your application with `flutter run --verbose` and attach all the
      log output below between the lines with the backticks. If there is an
      exception, please see if the error message includes enough information
      to explain how to solve the issue.
-->

[run.log](https://github.com/flutter/flutter/files/5255147/run.log)

<!--
     Run `flutter analyze` and attach any output of that command below.
     If there are any analysis errors, try resolving them before filing this issue.
-->

```
$ flutter analyze

Analyzing gallery...                                                    
No issues found! (ran in 1.8s)
```

<!-- Finally, paste the output of running `flutter doctor -v` here. -->

```
$ flutter doctor -v    
[✓] Flutter (Channel master, 1.22.0-10.0.pre.269, on Linux, locale en_US.UTF-8)
    • Flutter version 1.22.0-10.0.pre.269 at /home/ishitatsuyuki/Documents/flutter
    • Framework revision 51fa704642 (2 days ago), 2020-09-19 11:27:04 -0700
    • Engine revision 4b8477d115
    • Dart version 2.10.0 (build 2.10.0-142.0.dev)

[✗] Android toolchain - develop for Android devices
    ✗ Unable to locate Android SDK.
      Install Android Studio from: https://developer.android.com/studio/index.html
      On first launch it will assist you in installing the Android SDK components.
      (or visit https://flutter.dev/docs/get-started/install/linux#android-setup for detailed instructions).
      If the Android SDK has been installed to a custom location, please use
      `flutter config --android-sdk` to update to that location.


[✓] Linux toolchain - develop for Linux desktop
    • clang version 10.0.1
    • cmake version 3.18.2
    • ninja version 1.10.1
    • pkg-config version 1.7.3

[!] Android Studio (not installed)
    • Android Studio not found; download from https://developer.android.com/studio/index.html
      (or visit https://flutter.dev/docs/get-started/install/linux#android-setup for detailed instructions).

[✓] Connected device (1 available)
    • Linux (desktop) • linux • linux-x64 • Linux

! Doctor found issues in 2 categories.
```

</details>

OS: Arch Linux, Flutter set up from git master

Graphics: Mesa 20.1.8, AMDGPU, Skia using GLES backend