C#: Add test exposing missing delegate flow

Author: hvitved

csharp/ql/test/library-tests/dataflow/global/GetAnOutNode.expected

@@ -196,7 +196,7 @@
 | GlobalDataFlow.cs:472:25:472:50 | call to method ConfigureAwait | return | GlobalDataFlow.cs:472:25:472:50 | call to method ConfigureAwait |
 | GlobalDataFlow.cs:473:23:473:44 | call to method GetAwaiter | return | GlobalDataFlow.cs:473:23:473:44 | call to method GetAwaiter |
 | GlobalDataFlow.cs:474:22:474:40 | call to method GetResult | return | GlobalDataFlow.cs:474:22:474:40 | call to method GetResult |
-| GlobalDataFlow.cs:486:44:486:47 | delegate call | return | GlobalDataFlow.cs:486:44:486:47 | delegate call |
+| GlobalDataFlow.cs:498:44:498:47 | delegate call | return | GlobalDataFlow.cs:498:44:498:47 | delegate call |
 | Splitting.cs:8:17:8:31 | [b (line 3): false] call to method Return | return | Splitting.cs:8:17:8:31 | [b (line 3): false] call to method Return |
 | Splitting.cs:8:17:8:31 | [b (line 3): true] call to method Return | return | Splitting.cs:8:17:8:31 | [b (line 3): true] call to method Return |
 | Splitting.cs:20:22:20:30 | call to method Return | return | Splitting.cs:20:22:20:30 | call to method Return |

csharp/ql/test/library-tests/dataflow/global/GlobalDataFlow.cs

@@ -474,6 +474,18 @@ public void M4()
         var sink45 = awaiter.GetResult();
         Check(sink45);
     }
+
+    void M5(bool b)
+    {
+        void Inner(Action<string> a, bool b, string arg)
+        {
+            if (b)
+                a = s => Check(s);
+            a(arg);
+        }
+
+        Inner(_ => {}, b, "taint source");
+    }
 }
 
 static class IEnumerableExtensions