Remove OneWayToSource binding from BindingDemo.

Until #2983 is fixed.

samples/BindingDemo/MainWindow.xaml

@@ -24,7 +24,9 @@
             <TextBox Watermark="Two Way" UseFloatingWatermark="True" Text="{Binding Path=StringValue}" Name="first"/>
             <TextBox Watermark="One Way" UseFloatingWatermark="True" Text="{Binding Path=StringValue, Mode=OneWay}"/>
             <TextBox Watermark="One Time" UseFloatingWatermark="True" Text="{Binding Path=StringValue, Mode=OneTime}"/>
-            <TextBox Watermark="One Way to Source" UseFloatingWatermark="True" Text="{Binding Path=StringValue, Mode=OneWayToSource}"/>
+            <!-- Removed due to #2983: reinstate when that's fixed.
+              <TextBox Watermark="One Way to Source" UseFloatingWatermark="True" Text="{Binding Path=StringValue, Mode=OneWayToSource}"/>
+            -->
           </StackPanel>
           <StackPanel Margin="18" Spacing="4" Width="200">
             <TextBlock FontSize="16" Text="Collection Bindings"/>