Minor. Add regression test for KT-18292

#KT-18292: Obsolete

compiler/testData/diagnostics/testsWithStdLib/coroutines/kt18292.kt

@@ -0,0 +1,18 @@
+// SKIP_TXT
+// WITH_RUNTIME
+
+import kotlin.coroutines.experimental.*
+
+interface Job : CoroutineContext.Element {}
+interface Deferred<out T> : Job {
+    suspend fun await(): T
+}
+fun <T> async(<!UNUSED_PARAMETER!>block<!>: suspend () -> T): Deferred<T> = TODO()
+
+suspend fun fib(n: Long) =
+    async {
+        when {
+            n < 2 -> n
+            else -> <!TYPECHECKER_HAS_RUN_INTO_RECURSIVE_PROBLEM!>fib(n - 1)<!>.<!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>await<!>() <!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>+<!> fib(n - 2).<!DEBUG_INFO_ELEMENT_WITH_ERROR_TYPE!>await<!>()
+        }
+    }