Updated OmniXAML

To see if it fixed nested markup extensions. Doesn't seem to have had.

samples/XamlTestApplicationPcl/TextBox.paml

@@ -26,12 +26,8 @@
               <Panel>
                 <TextBlock Name="watermark"
                            Opacity="0.5"
-                           Text="{TemplateBinding Watermark}">
-                  <TextBlock.IsVisible>
-                    <Binding RelativeSource="{RelativeSource TemplatedParent}"
-                             SourcePropertyPath="Text"
-                             Converter="{Static local:StringNullOrEmpty.Instance}"/>
-                  </TextBlock.IsVisible>
+                           Text="{TemplateBinding Watermark}"
+                           IsVisible="{TemplateBinding Path=Text, Converter={Static local:StringNullOrEmpty.Instance}}">
                 </TextBlock>
                 <TextPresenter Name="PART_TextPresenter"
                                CaretIndex="{TemplateBinding CaretIndex}"

src/Markup/Perspex.Markup.Xaml/OmniXAML

@@ -1 +1 @@
-Subproject commit 81afc557c85473ba5035039c89253c1e0fe03927
+Subproject commit 99d24a3019504b901742496fffbdbb549a7245ab