C#: Add some property test cases.

Author: michaelnebel

csharp/ql/test/utils/modelgenerator/dataflow/CaptureSummaryModels.expected

@@ -1,3 +1,5 @@
+| NoSummaries;Properties;false;get_Prop;();;Argument[this];ReturnValue;taint;df-generated |
+| NoSummaries;Properties;false;set_Prop;(System.Object);;Argument[0];Argument[this];taint;df-generated |
 | NoSummaries;PublicClassFlow;false;PublicReturn;(System.Object);;Argument[0];ReturnValue;taint;df-generated |
 | Summaries;BaseClassFlow;true;ReturnParam;(System.Object);;Argument[0];ReturnValue;taint;df-generated |
 | Summaries;BasicFlow;false;ReturnField;();;Argument[this];ReturnValue;taint;df-generated |
@@ -36,3 +38,5 @@
 | Summaries;IEnumerableFlow;false;ReturnIEnumerableElement;(System.Collections.Generic.IEnumerable<System.Object>);;Argument[0].Element;ReturnValue;taint;df-generated |
 | Summaries;OperatorFlow;false;OperatorFlow;(System.Object);;Argument[0];Argument[this];taint;df-generated |
 | Summaries;OperatorFlow;false;op_Addition;(Summaries.OperatorFlow,Summaries.OperatorFlow);;Argument[0];ReturnValue;taint;df-generated |
+| Summaries;Properties;false;get_Prop1;();;Argument[this];ReturnValue;taint;df-generated |
+| Summaries;Properties;false;set_Prop2;(System.String);;Argument[0];Argument[this];taint;df-generated |

csharp/ql/test/utils/modelgenerator/dataflow/NoSummaries.cs

@@ -162,3 +162,13 @@ public object HasNeutralSummaryNoFlow(object o)
         return null;
     }
 }
+
+public class Properties
+{
+    public object backingField;
+    public object Prop
+    {
+        get { return backingField; }
+        set { backingField = value; }
+    }
+}

csharp/ql/test/utils/modelgenerator/dataflow/Summaries.cs

@@ -260,3 +260,18 @@ public override int GetHashCode()
         return intTainted;
     }
 }
+
+public class Properties
+{
+    private string tainted;
+
+    public string Prop1
+    {
+        get { return tainted; }
+    }
+
+    public string Prop2
+    {
+        set { tainted = value; }
+    }
+}