[Tests] Migrate backend-independent tests from native to compiler/testData.

^KT-65979

compiler/testData/codegen/box/branching/when_through.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the LICENSE file.
+ */
+// WITH_STDLIB
+
+import kotlin.test.*
+
+fun when_through(i: Int): Int {
+  var value = 1
+  when (i) {
+    10 -> value = 42
+    11 -> value = 43
+    12 -> value = 44
+  }
+
+  return value
+}
+
+fun box(): String {
+  val res = when_through(2)
+  if (res != 1) return "FAIL $res"
+
+  return "OK"
+}