[Misc] Enable @Experimental project-wide

build.gradle.kts

@@ -331,6 +331,7 @@ allprojects {
     configureJvmProject(javaHome!!, jvmTarget!!)
 
     val commonCompilerArgs = listOfNotNull(
+        "-Xuse-experimental=kotlin.Experimental",
         "-Xallow-kotlin-package",
         "-Xread-deserialized-contracts",
         "-Xjvm-default=compatibility",

core/descriptors/src/org/jetbrains/kotlin/types/checker/ClassicTypeSystemContext.kt

@@ -593,7 +593,6 @@ fun Variance.convertVariance(): TypeVariance {
 }
 
 
-@Suppress("EXPERIMENTAL_IS_NOT_ENABLED")
 @UseExperimental(ExperimentalContracts::class)
 fun requireOrDescribe(condition: Boolean, value: Any?) {
     contract {