[Wasm] Minor: remove unused stdlib stub

Merge-request: KT-MR-8140
Merged-by: Svyatoslav Kuzmich <svyatoslav.kuzmich@jetbrains.com>

libraries/stdlib/wasm/stubs/testHelpers.kt

@@ -1,21 +0,0 @@
-/*
- * Copyright 2010-2020 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 kotlin.test
-
-import kotlin.internal.InlineOnly
-import kotlin.internal.OnlyInputTypes
-
-// TODO: Remove this once we support CLASS_REFERENCE IR node
-@InlineOnly
-public inline fun <reified T : Throwable> assertFailsWith(message: String? = null, block: () -> Unit): T {
-    var throwable: Throwable? = null
-    try {
-        block()
-    } catch (e: Throwable) {
-        throwable = e
-    }
-    return throwable as? T ?: throw AssertionError("assertFailsWith failed: $message")
-}