Add regression test for KT-20744

#KT-20744: Obsolete

compiler/testData/codegen/box/coroutines/featureIntersection/delegate.kt

@@ -0,0 +1,27 @@
+// WITH_RUNTIME
+// WITH_COROUTINES
+
+import helpers.*
+import kotlin.coroutines.experimental.*
+import kotlin.properties.Delegates
+
+class Pipe {
+    var value = 0
+    suspend fun send(value: Int) {
+        this.value = value
+    }
+}
+
+fun builder(c: suspend () -> Unit) {
+    c.startCoroutine(EmptyContinuation)
+}
+
+val pipe = Pipe()
+
+var mode by Delegates.observable(0) {_, _, value -> builder { pipe.send(value) }}
+
+fun box() : String {
+    mode = 42
+    if (pipe.value != 42) return "FAIL"
+    return "OK"
+}