Bug 259634 – WebKit incorrectly renders upper left quarter of page scaled to the full view size on M1 running Linux

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKitGTK

### Broken:

 * Epiphany version: 45.beta-3-g753bfa489 (nightly and manual build from latest source)
 * WebKitGTK version: WebKitGTK 2.41.6
 * Distributor: Gnome-Nightly Flatpak, source

### Working:

 * Epiphany version: 44.6
 * WebKitGTK version: WebKitGTK 2.40.4
 * Distributor: Flathub

### System specs:

 * OS: Fedora 38 Workstation
 * Desktop: GNOME 44 (on Wayland)
 * Device: Apple MacBook Air M1
 * Kernel: Linux 6.4.4-402.asahi.fc38.aarch64
 * Mesa info:
   ```
   $ glxinfo | grep OpenGL
   OpenGL vendor string: Mesa
   OpenGL renderer string: Apple M1 (G13G B1)
   OpenGL core profile version string: 3.1 Mesa 23.3.0-devel
   OpenGL core profile shading language version string: 1.40
   OpenGL core profile context flags: (none)
   OpenGL core profile extensions:
   OpenGL version string: 3.1 Mesa 23.3.0-devel
   OpenGL shading language version string: 1.40
   OpenGL context flags: (none)
   OpenGL extensions:
   OpenGL ES profile version string: OpenGL ES 3.0 Mesa 23.3.0-devel
   OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.00
   OpenGL ES profile extensions:
   ```

### Description:

On my ARM64 MacBook Air laptop (Apple Silicon M1), the webpage renders ridiculously zoomed in. It's like it's taking the upper left quarter of the rendered page, and zooming it to fill the whole viewport. This only happens at display scaling above 100%, including integer and fractional scaling. At every scaling setting >100, the same behavior can be observed. At 100% scaling, it renders correctly.

### Screenshots:

https://gitlab.gnome.org/GNOME/epiphany/uploads/09837676f6d0e728a310316fd03ea3d3/Screenshot_from_2023-07-30_12-06-05.png
https://gitlab.gnome.org/GNOME/epiphany/uploads/46083cba639d5f89dd1e954a00c87e27/Screenshot_from_2023-07-30_12-05-29.png
https://gitlab.gnome.org/GNOME/epiphany/uploads/60ddf4b8e4012202ff06efd1d0d8a040/Screenshot_from_2023-07-30_12-04-16.png
*Pictured above: Top left quarter of WebKit element filling the whole viewport at fractional scale of 175%*

https://gitlab.gnome.org/GNOME/epiphany/uploads/8b2425b5f6dc94e0b4eb37563d0f611c/Screenshot_from_2023-07-30_12-12-39.png
*Pictured above: Epiphany Devel at 200% display scaling*

https://gitlab.gnome.org/GNOME/epiphany/uploads/906d2e4abfca7ae2d97f1c42946f25f8/Screenshot_from_2023-07-30_12-12-50.png
*Pictured above: Epiphany Devel at 100% display scaling*

https://gitlab.gnome.org/GNOME/epiphany/uploads/e926d154d16003de84f6224def7972e6/Screenshot_from_2023-07-30_12-09-21.png
*Pictured above: Latest stable release not presenting this issue*

### Additional notes:

This may be a GTK4 scaling issue, a problem with the Asahi OpenGL 3.1 GPU drivers, or a WebKit issue. The GNOME/Epiphany issue can be found here: https://gitlab.gnome.org/GNOME/epiphany/-/issues/2141

Oh, and for some more detailed information, here is what the log says when I first run Epiphany:

```
Application started at 12:45:44 PM
libEGL warning: egl: failed to create dri2 screen
libEGL warning: failed to get driver name for fd 0

libEGL warning: MESA-LOADER: failed to retrieve device information

libEGL warning: failed to get driver name for fd 0

libEGL warning: egl: failed to create dri2 screen
libEGL warning: egl: failed to create dri2 screen
```

[Kdwk]

> libEGL warning: egl: failed to create dri2 screen

Looks like this is happening everywhere and not a hardware-specific problem. I've seen it on Intel and Nvidia hardware, and now Apple hardware as well

Still an issue in WebKitGTK 2.41.91 and Epiphany Technology Preview 45.beta-44-gad36cb3ba+

This issue still affects the stable GNOME Web 45.2, but is fixed in the latest nightly.