C#: Add new testexamples and update expected testoutput.

Author: michaelnebel

csharp/ql/test/query-tests/Likely Bugs/StaticFieldWrittenByInstance/StaticFieldWrittenByInstance.cs

@@ -26,4 +26,21 @@ void InstanceTest()
         staticField = 0;    // BAD
         instanceField = 0;  // OK
     }
+
+    static object backingField;
+    static object StaticProp
+    {
+        get
+        {
+            return backingField ?? (backingField = new object()); // OK
+        }
+    }
+
+    object Prop
+    {
+        get
+        {
+            return backingField ?? (backingField = new object()); // BAD
+        }
+    }
 }

csharp/ql/test/query-tests/Likely Bugs/StaticFieldWrittenByInstance/StaticFieldWrittenByInstance.expected

@@ -1,2 +1,3 @@
-| StaticFieldWrittenByInstance.cs:15:9:15:19 | access to field staticField | Write to static field from instance method or constructor. |
-| StaticFieldWrittenByInstance.cs:26:9:26:19 | access to field staticField | Write to static field from instance method or constructor. |
+| StaticFieldWrittenByInstance.cs:15:9:15:19 | access to field staticField | Write to static field from instance method, property or constructor. |
+| StaticFieldWrittenByInstance.cs:26:9:26:19 | access to field staticField | Write to static field from instance method, property or constructor. |
+| StaticFieldWrittenByInstance.cs:43:37:43:48 | access to field backingField | Write to static field from instance method, property or constructor. |