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

^KT-65979

compiler/testData/codegen/box/object/fields.kt

@@ -0,0 +1,26 @@
+/*
+ * 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.*
+
+private var globalValue = 1
+var global:Int
+    get() = globalValue
+    set(value:Int) {globalValue = value}
+
+fun globalTest(i:Int):Int {
+    global += i
+    return global
+}
+
+
+fun box(): String {
+    assertEquals(1, global)
+    assertEquals(42, globalTest(41))
+    assertEquals(42, global)
+
+    return "OK"
+}