Added tests on class delegation

backend.native/tests/codegen/classDelegation/withBridge.kt

@@ -0,0 +1,28 @@
+interface A<T> {
+    fun foo(t: T): String
+}
+
+interface B {
+    fun foo(t: Int) = "B"
+}
+
+class Z : B
+
+class Z1 : A<Int>, B by Z()
+
+fun box(): String {
+    val z1 = Z1()
+    val z1a: A<Int> = z1
+    val z1b: B = z1
+
+    return when {
+        z1.foo( 0)  != "B" -> "Fail #1"
+        z1a.foo( 0) != "B" -> "Fail #2"
+        z1b.foo( 0) != "B" -> "Fail #3"
+        else -> "OK"
+    }
+}
+
+fun main(args: Array<String>) {
+    println(box())
+}