Drop deprecated -Xexperimental flag from compiler and tests

compiler/tests/org/jetbrains/kotlin/codegen/JvmModuleProtoBufTest.kt

@@ -96,15 +96,4 @@ class JvmModuleProtoBufTest : KtUsefulTestCase() {
     fun testJvmPackageNameMultifileClass() {
         doTest("/moduleProtoBuf/jvmPackageNameMultifileClass")
     }
-
-    fun testExperimental() {
-        doTest(
-            "/moduleProtoBuf/experimental", extraOptions = listOf(
-                "-Xopt-in=kotlin.RequiresOptIn",
-                "-Xexperimental=org.foo.A",
-                "-Xexperimental=org.foo.B.C",
-                "-Xopt-in=org.foo.D"
-            )
-        )
-    }
 }

compiler/tests/org/jetbrains/kotlin/jvm/compiler/ExperimentalIntegrationTest.kt

@@ -1,36 +0,0 @@
-/*
- * Copyright 2000-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package org.jetbrains.kotlin.jvm.compiler
-
-import org.jetbrains.kotlin.cli.js.K2JSCompiler
-import java.io.File
-
-class ExperimentalIntegrationTest : AbstractKotlinCompilerIntegrationTest() {
-    override val testDataPath: String
-        get() = "compiler/testData/experimental/"
-
-    fun testJvmExperimentalModule() {
-        val lib = compileLibrary(
-            "lib", additionalOptions = listOf(
-                "-Xopt-in=kotlin.RequiresOptIn",
-                "-Xexperimental=lib.ExperimentalAPI"
-            ),
-            checkKotlinOutput = { output -> assertTrue(output, output.trimEnd().endsWith("OK")) }
-        )
-        compileKotlin("usage.kt", tmpdir, listOf(lib))
-    }
-
-    fun testJsExperimentalModule() {
-        val lib = compileJsLibrary(
-            "lib", additionalOptions = listOf(
-                "-Xopt-in=kotlin.RequiresOptIn",
-                "-Xexperimental=lib.ExperimentalAPI"
-            ),
-            checkKotlinOutput = { output -> assertTrue(output, output.trimEnd().endsWith("OK")) }
-        )
-        compileKotlin("usage.kt", File(tmpdir, "usage.js"), listOf(lib), K2JSCompiler())
-    }
-}