Auto merge of #17984 - Manishearth:rm-testing, r=SimonSapin

Remove style/testing feature

We added this because a year ago we had no reliable Gecko CI. This meant that Gecko-only properties needed to be tested *somehow*, and we solved that by making it so that for unit tests we compile all properties, not just the servo ones.

This was useful back then, but I don't think we need this anymore. We have reliable Gecko CI, and all the gecko-only stuff we tested is adequately handled by the properties-database parsing mochitests. It's a bit of annoying cruft that just complicates things; we probably should remove it.

r? @emilio or @SimonSapin

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ports/geckolib/Cargo.toml

@@ -11,7 +11,6 @@ crate-type = ["staticlib", "rlib"]
 
 [features]
 bindgen = ["style/use_bindgen"]
-testing = ["style/testing"]
 gecko_debug = ["style/gecko_debug"]
 
 [dependencies]

ports/servo/Cargo.toml

@@ -32,7 +32,6 @@ default = ["webdriver", "max_log_level"]
 max_log_level = ["log/release_max_level_info"]
 webdriver = ["libservo/webdriver_server"]
 energy-profiling = ["libservo/energy-profiling"]
-testing = ["libservo/testing"]
 debugmozjs = ["libservo/debugmozjs"]
 
 [dependencies]