[NI] Don't process lambda until expected type will be fixed

compiler/testData/codegen/box/regressions/lambdaPostponeConstruction.kt

@@ -0,0 +1,14 @@
+class MyList<T>
+
+operator fun <T> MyList<T>.plusAssign(element: T) {}
+
+val listOfFunctions = MyList<(Int) -> Int>()
+
+fun foo() {
+    listOfFunctions.plusAssign({ it -> it })
+    listOfFunctions += { it -> it }
+}
+
+fun box(): String {
+    return "OK"
+}