Generate bridges for delegates

compiler/testData/codegen/bridges/delegation.kt

@@ -0,0 +1,11 @@
+trait A<T> {
+    fun foo(): T
+}
+
+class B : A<String> {
+    override fun foo() = "OK"
+}
+
+class C(a: A<String>) : A<String> by a
+
+fun box() = (C(B()) : A<String>).foo()

compiler/testData/codegen/bridges/delegationProperty.kt

@@ -0,0 +1,15 @@
+trait A<T> {
+    var result: T
+}
+
+class B(a: A<String>): A<String> by a
+
+fun box(): String {
+    val o = object : A<String> {
+        override var result = "Fail"
+    }
+    val b: A<String> = B(o)
+    b.result = "OK"
+    if (b.result != "OK") return "Fail"
+    return (b : A<String>).result
+}

compiler/testData/codegen/bridges/substitutionInSuperClassDelegation.kt

@@ -0,0 +1,17 @@
+trait A<T> {
+    fun id(t: T): T
+}
+
+open class B : A<String> {
+    override fun id(t: String) = t
+}
+
+class C : B()
+
+class D : A<String> by C()
+
+fun box(): String {
+    val d = D()
+    if (d.id("") != "") return "Fail"
+    return (d : A<String>).id("OK")
+}