Improve font rendering on Linux, i submited a PR

[Ryuukk KOKO]

Hello,

Light text on dark background, specially with grayscale anti aliasing is looking very blurry on Linux

This is all because chromium changes Skia's gamma correction values to outdated values

Freetype recomand to use 1.8 for gamma correction, yet Chromium's devs are using 1.2 LOL

Please review my PR, state of chromium on linux is very sad (i moved to firefox for the time being)

https://chromium-review.googlesource.com/c/chromium/src/+/5332813/1..2/skia/BUILD.gn