Check Fontations Rust font stack library

[uazo]

chromium is preparing to gradually activate rust. The first test they are doing is the use of Fontation and and will arrive in android

currently cromite is build with

• enable_rust = true <-- default
• enable_all_rust_features = false <-- default
• use_typeface_fontations = false <-- default

so kFontationsFontBackend is not accessible in chrome://flags and actually is disabled

since it is not clear to me what it does should be tested to see if patch Fonts-fingerprinting-mitigation.patch requires modifications

[uazo]

checked, rust is used for web font management. in any case, I know nothing about rust...